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Materia Photographica 


A Dictionary of the Chemicals, Raw 
Materials, Developing Agents 
and Dyes used in 
Photography 


BY 


week DB. HITCHINS, Pu. D. 
F.R.P.S., F.R.M.S., F.C.S., F.PH.S.L. 


Member of Society of Motion Picture Engineers 


a 


PHILADELPHIA 
Frank V. CHAmpers, Publisher 


636 FRANKLIN SQUARE 


-<P—|HE intent and purpose of the author of the 
AY] ensuing pages which are devoted to considera- 
Ni tion of the “Materia Photographica” em- 
ployed in the photographic art, is to present 
an exhaustive dictionary of the raw materials, 
chemical bodies, as well as the specific dyes and devel- 
oping agents necessary to a complete performance in 
the various provinces of photography. 


There has been a longing desire on the part of the 
practical manipulator, as well as the experimentalist, 
to have a sort of vade mecum of this kind, concise, yet 
comprehensive, and withal intelligible to those not 
essentially scientific chemists. There is no work in 
America which undertakes this problem, and this book 
will, therefore, fill the requirements completely. The 
author is thoroughly conversant with the topic under 
treatment and has labored strenuously to insure ac- 
curacy in the detail information and.to explore thor- 
oughly the entire field of operation. 


It is, therefore, something indispensable, not only to 
the experimentalist, but of pertinent value to the entire 


profession. 
THE PUBLISHER. 


4 MATERIA PHOTOGRAPHICA 


INTERNATIONAL ATOMIC WEIGHTS 


Symbol 


Aluminum, octs eG ae eee Al 
Antimony . 7 i0Gs2045 coho 1a Coen ee Sb 
ATHON GS pas cota oe lea Ne Sane A 
Arsenic, 643 (dee ee eee As 
Barittm, .os. corn ee eee Ba 
Bismuth... 2043 ae ee eee Bi 
Borotiin soccer ake ae eee B 
Bromine, 2. 3s oe eee Br 
Cadmium see. Soe ee eee eee Cd 
Caletiom oof Ree en ee ee Ca 
Carbon cc fone ee ae eee 
Cerium [ius £245 3S eh ee Ce 
Cesium. es 25 oo ee eee Cs 
Chiorine. 2.6.0 Syed eee eee Cl 
Chromium. 2... 505. ee ee eee Cr 
Cobalt ..2.556. ae a eee Co 
Columbium: 3. (6h60h.4e.. bk oe Cb 
Copper. . Woe vue br sun Cu 
Dysprosium:..2)s9.1 2 Se eee Dy 
Erbium 2.20 oo yet oe eee eee Er 
Furopium / 25: %. ste oe eee Eu 
Fluorine. ..3..03.045). 5 oe ie eee F 
adolium :.4\.5 ss, 4s 4. eke a one Gd 
Galliam 02. 2 ee ane Ga 
Germanium ..../..4.'.4 20 ee eee Ge 
Glucinum... oc50 2. Sa ee eee Gl 
Golda. oo. SRE ea Au 
Helium 2... Se eee He 
Holmium. 2... 23 he eee Ho 
Hydrogen 2). 5.2. scene H 
Indium... 62. 3 ee ee In 
lodinenc.%, 33 ea ee eee J 
Tridiumss3 265.0. ee ee eee Ir 
Tron. ste ee he eee Fe 
Krypton 0. ce ee ee eee Kr 
Lanthanum. :. 097-4530 ee eee La 
Lead. ooo... 0c ee Pb 


Atomic 
Weight 


MATERIA PHOTOGRAPHICA 


Symbol 


GL ER UN eae Si i Lu 
LOE oo Gl leer Mg 
SU STRESSES i Mn 
ESTAS oon! SS 60 ein eerie Hg 
aoe NTGR Cave deans cede lee ee es Mo 
OEE So |e ra Nd 
em, Sac wale case wesls wees Ne 
NR dhs ys einsnse < als a nb c/s 0, oe Ni 
Petonetraditm emaration).............3.. Nt 
Oey oe N 
We ie cs ied accie wind wise oat od es Os 
i 5 cia gievessa s wit sie med a ets O 
ES ee Gy a a rr Pd 
GG Fe bled sae sles ben eae we we P 
AAO oo i a re Pt 
[> Sef RESTOR oo 5 ay, K 
CEL TONS EUS Cy on are aan Pr 
SENS SITD, BUS a rar Ra 
OS ESEOUNIV hea Pt aa CS a a Rh 
OOPS A373) coal ae eee ani Rb 
UO SEC TT jose arr el pen ae Ru 
eR UO he oe givin siwih' pe nln > Boece Sa 
WO SISSLER Fue 1 i tn cr rn Sc 
CE rR Pe a a ces eos Begg Se 
OO OE no eh Sa rr Si 
Ok Se Ag 
EWS lie A) ety oe rr Na 
OS OMELET oad sR ee a Sr 
“ULEEENURT' 5 4 5. Op UES S 
USES SOE 6 2 ed ae Ta 
“OP USTER DELS ES a e 
De TURTON te eet 21s foo 13 «oi a's .0 6 a5s, 308s Soh Tb 
BPN his gas ick asec o's 8 hale Laie ba.e art 
MRT IE, ok is wires cade avekas Th 
Tn Sy 7 SR a a ro Tm 
SLT oye Ee Sn 
SSE a rr Ti 
ee Lacie cue cs hae Gace sais a sivas W 
EN ey Aue opts oie die od wo Od whe U 
CURING GAUTT VE, anak 5 tags Oia eg ee Ba V 
ee ess alg cas vy oe cle taesos Xe 
Ytterbium (Neoytterbium)................ Yb 
Sen, k= a re er ate Yt 
TNE ey a Zn 


Atomic 
Weight 


175.0 
24.32 
99.93 

200.6 
96.0 

144.3 


6 MATERIA PHOTOGRAPHICA 


ABBREVIATIONS USED IN DESCRIBING 
MATERIALS 


A.P.—Average price 

A.W.—Atomic weight 

B.P.—Boiling point 

Der.— Derivation 

Fr.—French 

Ger.—German 

G.—Grade suitable for photographic use 
Ins.—Insoluble 

M.P.—Melting point 
M.W.—Molecular weight 
P.—Properties 

Sap.—Soluble in all proportions 
Sol.—Soluble 

Sp.G.—Specific Gravity 

Ss.—Slightly soluble 

Syn.—Synonym 

U.P.—wUses in photography 
C.P.—Chemically pure 
U.S.P.—United States Pharmacopzia 


owes: 


"NEWARK CAMERA GLUB 


4 
& 


BEWARK NDW JERSEY 


MATERIA PHOTOGRAPHICA 7 


MATERIA PHOTOGRAPHICA 


‘General Chemicals and Raw Materials 


ACETONE, (CH:;)2CO 
Fr. Acétone; Ger. Aceton 


Syn. Dimethyl-ketone, Ketopropane, Methylacetal, Prop- 
anone, Pyroacetic ether. 


M. W. 58: Sp. G. about 0.798°: M. P. 94.3°C: B. P. 56.48°C. 
Sol. in water, alcohol and ether. 


P. Colorless liquid, mint-like odor, highly volatile and 
inflammable. Should be kept in well stoppered bottles in 
a cool place. 

Der. By dry distillation of calcium acetate also as a by- 
product in the manufacture of butyl alcohol. Purified by 
rectification. ; 

G. Technical; U.S.P. (98% Acetone). Should not show 
more than a trace of acidity. 

U. P. Solvent for resins, collodion, nitrocellulose; used in 
manufacture of sheet celluloid, varnishes and film 
cements, can be used as a substitute for the alkali in pyro 
or hydroquinone developers. 

The acid amidol developer can be remarkably energized 
by the addition of from 3 to 5% acetone. 


ACETONE SULPHITE, NaHSOs (CH:;)2CO H.0 
Fr. Acétone Sulfite; Ger. Acetonsulphit 
M. W. 162. 


Sol. in water; Ss. in alcohol. 
P. Fine white Powder. 
Der. Acetone combined with acid sodium sulphite. 


8 MATERIA PHOTOGRAPHICA 


U. P. Substitute for sodium sulphite and the metabisulphites 
in development. 10 parts acetone sulphite are equal to 7.5 
parts of potassium metabisulphite or 20 parts of dry 
sodium sulphite. 


_ As a preservative of pyro, % ounce of acetone sulphite 
is added for each ounce of pyro used. Keeps fixing baths 
clear and colorless. 


ACID ACETIC, HC.H:O, 
Fr. Acide Acétique; Ger. Essigsaure 


Syn. Acid methanecarboxylic, Vinegar acid, Purified Pyro- 
ligneous acid. 


Mew. 00° M..P216.7° CSB Pr lisa: 
Sol. in water, alcohol, ether, chloroform and glycerine. 


P. Colorless liquid, sour pungent smell, vapor inflammable, 
congeals at 15.65°C., 


Der. Prepared from wood by destructive distillation, also by 
the oxidation of dilute ethyl alcohol, governed by bacterial 
action. 


G. Two grades commonly used in photography, Glacial 
Acetic Acid, U.S.P. (99% acetic acid) Sp. G. about 1.065, 
congeals at about 12.8°C. hence the name glacial (or ice 
like) acetic acid. Commercial grade (28% acetic acid) 
Sp. G. 1.038; This strength acid can be easily prepared 
from the glacial acid by dilution with distilled water. 
Glacial acetic acid is a strong escharotic, if spilt on the 
skin should be washed off at once. ‘The impurities often 
found in acetic acids are sulphurous acid, tarry matters, 
hydrochloric or sulphuric acid. Samples which yield a 
precipitate when a drop of silver nitrate solution is added 
to a quarter of an ounce, or which discolor when the 
mixture is exposed to light, should be rejected. 


U. P. Preparation of acid fixing baths. As a clearing bath 
after ferrous oxalate development of bromide paper. Used 
in the uranium toning bath facilitates the penetration of 
the gelatine by the bath. Solvent for gelatine, celluloid, 
pyroxyline. Used in the manufacture of cellulose acetate. 
Preparation of gelatine substratum. 


MATERIA PHOTOGRAPHICA 9 


ACID BENZOIC, C.H;COOH 
Fr. Acide Benzoique.; Ger. Benzoesaure 
Syn. Acid phenylformic. 
Bee) ee op. G. 1.2659: M. P. 121.25°C, B. P. 249.2°C. 


Sol. in alcohol and ether; Ss. in water. Freely soluble in 
chloroform or benzene. 


P. White voluminous crystalline plates or needles. Aromatic 
odor. 


Der. From gum benzoin by sublimation. Industrially, by the 
chlorination of toluol, heating this under pressure with 
milk of lime. The benzoic acid is distilled off by steam 
and crystallized. 


G. U.S.P. from benzoin. 


U. P. Has been used as a preservative in photographic emul- 
sions, used in toning baths and for the sizing and sur- 
facing of photographic paper. 


ACID BORIC, H;:BO; 
Fr. Acide Borique; Ger. Borsaure 


Syn. Acid boracic, Acid orthoboric. 

M. W. 62: Sp. G. 1.4347: M. P. 184°C. 

Sol. in water, alcohol, glycerine, and volatile oils. 
P. White shining scales or amorphous powder. 


Der. By the addition of hydrochloric or sulphuric acid to a 
solution of borax and crystallizing. 


G. U.S.P. crystal or powder. 


U. P. Used in pyro developers as a restrainer and to prevent 
stains, can also be used in the fixing bath as a stain pre- 
venter. A solution of 1 part boric acid in 30 parts of 
water acts as a stop bath, stopping development instantly. 


10 MATERIA PHOTOGRAPHICA 


ACID CARBOLIC (Phenol), C,.H;OH 
Fr. Acide Phénique; Ger. Karbolsaure 


Syn. Phenic acid, Phenyl hydrate, Hydroxybenzene. 
M. W. 94: Sp. G. 1.0677: M. P. 42:5°C.> BaP iain ee 


Sol. in water, alcohol, ether, chloroform, glycerine and 
alkalis. 

P. White crystalline mass, turns pink or red if not pure, 
absorbs water from the air and liquefies, has sharp burn- 
ing taste and distinctive odor, strong corrosive poison. 


Der. By treating coal tar oil fraction, boiling between 170° 
and 230°C. with caustic soda to form phenolate. The 
solution is purified by removing the naphthalene, treated 
with acid to set the phenol free which is further purified 
by distillation. It can also be prepared by converting 
benzol into sulphonic acid and fusing the latter with 
caustic soda. On treating the sulphonate with acid, pure 
phenol is released. 

G. U.S.P. crystal or fused. 

U. P. Used as a preservative for photographic emulsions, 
gelatine solutions, and mountants. It is the starting point 
a many of the photographic chemicals, developers and 

yes. 


ACID CHROMIC (Anhydride), CrO; 
Fr. Acide Chromique; Ger. Chromsaure Anhydrid 


Syn. Chromium trioxide. 
M. W. 100: Sp.-G. 2:672°>M. Pr 19676 
Sol. in water. 


P. Reddish brown crystals. Violently explodes when brought 
into contact with organic substances. Highly poisonous. 


Der. Hydrochloric or sulphuric acid added to a solution of 
sociGma bichromate and the product recovered by recrystal- 
ization. 


GaAs ea 


U. P. Principal use in process work in the fish glue process. 
Used in conjunction with sulphuric acid for clearing the 
fish glue image previous to etching, removing any scum 
from between the half-tone dots. 


MATERIA PHOTOGRAPHICA 11 


ACID CITRIC, (CO:HCH:).C(OH)CO.H 
Fr. Acide Citrique; Ger. Citronensaure 


Syn. Acid oxytricarballylic. 
Beevee 2102 on. G, 1.542: M. P. 153°C, 
Sol. in water, alcohol and ether. 


P. Colorless, odorless crystals, with characteristic lemon 
flavor. 


Der. Crude citric acid is obtained from lemons or other 
citrus fruit, then neutralized with calcium carbonate and 
the lime salt dissociated with sulphuric acid. The product 
is then filtered, evaporated and recovered by crystalliza- 
tion. T'artaric acid is the most likely impurity to be 
expected. 

U.S.P. crystal or powder. 


G 

U. P. Citric acid can be used as a preservative in some 
developing solutions and in others acts as a restrainer. 
Can be used for making acid fixing baths and as a preser- 
vative in emulsions. 1 part citric acid to 100 of water is 
an excellent clearing bath for removing the yellow pyro 
stain from negatives. Used in the preparation of gelatino- 
citro-chloride printing-out paper. 

Citric acid can be used to replace acetic acid in pho- 

tographic solutions. 1 oz. of citric acid is equivalent to 
2 ozs. of 28% acetic acid. Citric acid will replace glacial 
acetic acid weight for weight. 


ACID DIGALLIC (Tannin), CHO. 
Fr. Acide Tannique; Ger. Gerbsaure 


Syn. Acid gallotannic. 

M. W. 322: M. P. Decomposes at 210°C. 

Sol. in water and alcohol; Ss. in ether. 

P. Lustrous, faintly yellow amorphous powder. 

Der. Extracted from powdered gall nuts with water and 
alcohol, then evaporated and purified by crystallization. 

eer. 2 

U. P. Principal use in process work as an ingredient in the 
etching solution for collotype plates acting as a hardener 
of the gelatine. Has been recommended as a hardening 


agent for prints and negatives, but is likely to give some 
stain. 


12 MATERIA PHOTOGRAPHICA 


ACID FORMIC, HCOOH H.CO: 
Fr. Acide Formique; Ger. Ameisensaure 
Syn. Acid hydrogen carboxylic. 
M. W.° 46: Sp. G.1.2178: M. P)8.3% CBee aii 
Sol. in water, alcohol and ether. 
P. Colorless liquid, pungent odor, very strong caustic. 


Der. By dissociation of sodium formate with mineral acid, 
then by distillation and absorption in distilled water. 
Purified by rectification. 


Cay WES eke) 


U. P. Comparatively unimportant in photography. Is some- 
times used in process work instead of acetic acid for 
stripping of wet collodion negatives. Its disadvantage is, 
however, its dangerous caustic properties. 


ACID GALLIC, C.H:(OH);CO.H.H20 3:4:5 
Fr. Acide Gallique; Ger. Gallussaure 
Syn. Acid Trioxybenzoic, Acid Trihydroxybenzoic. 
M. W. 188.06: Sp. G. 1.694: M. P. 220° to 240°C. 
Sol. in alcohol; Ss. in water and ether. 
P. Slightly yellow or colorless crystalline needles or prisms. 


Der. Obtained by fermentation from powdered galls or by 
boiling tannin with dilute acid or caustic soda. 


GU Sse: 


U. P. Not very much used in modern photography. In the 
early days of photography, was used as a developer for 
paper negatives. At the present time is occasionally used 
in the development of P. O. P., intensification of col- 
lodion and gelatine negatives, and as one of the ingredients 
in the ferrous citrate developer for chloride plates. Is 
used by lithographers for preparing the surface of zinc 
plates for printing. 


MATERIA PHOTOGRAPHICA 13 


ACID HYDROBROMIC, HBr in Aqueous Solution 
Fr. Acide Bromhydrique; Ger. Bromwasserstoffsaure 


Syn. Hydrogen bromide, Bromhydric acid. 
bea eects op. Gr 1.38. 

Sol. in water. 

P. Faintly yellow or clear colorless liquid. 


Der. Made by passing hydrogen with bromine vapor over a 
warm platinum sponge which acts as a catalyzer and then 
collecting by absorption in water. 


G. U.S.P. (40% HBr.) 


U. P. Used in the production of some of the bromides used 
in photography. Sometimes added to emulsions as a 
preservative. Small additions of hydrobromic acid will 
cure fog in an emulsion, at the same time decreasing the 
emulsion speed. 


ACID HYDROCHLORIC, HCl 
Fr. Acide Chlorhydrique; Ger. Chlorwasserstoffsaure 


Syn. Muriatic acid, Hydrogen chloride. 
hie Wer s0.0; op, G. 1.16. 


Sol. in water, miscible in all proportions with alcohol and 
water. 


P. Clear, colorless or slightly yellow. Fuming pungent 
liquid, poisonous. 


Der. Usually made by the action of sulphuric acid on com- 
mon salt. Also as a by-product of the LeBlanc soda 
process. 


Sees (33% HCL) 


U. P. Generally used as a clearing bath for pyro stains and 
as a clearing bath in the platinotype process. Is used in 
connection with vanadium, iron and the copper toning 
processes. 

The addition of HC! to chloride emulsions increases 
speed, also tends to make such emulsions clean working 
and free from fog. 


14 MATERIA PHOTOGRAPHICA 


ACID HYDROFLUORIC, HF 
Fr. Acide Fluorhydrique; Ger. Fluorwasserstoffsaure 


Syn. Hydrogen fluoride, Fluoric acid. 
M. W. 20. 
P. Clear, colorless fuming corrosive liquid. Very dangerous 


to handle. Dissolves the nails and produces terrible sores 
if allowed to come in contact with the skin. 


Der. Calcium fluoride is treated with sulphuric acid, the 
mixture distilled in a platinum retort. Hydrofluoric acid 
gas passes over and is dissolved in distilled water. 

G. Technical. 52% HF. 

U. P. Its principal use in photography is for stripping films 
from glass plates; a 2 to 3% solution being used. It is 
also used in hyalography or photographic etching on glass. 


ACID LACTIC, CH:CH(OH)COOH 
Fr. Acide Lactique; Ger. Milchsaure 


Syn. Acid alpha-hydroxypropionic and acid ethylidenelactic. 
M. W. 90: Sp. G. 1.2485. 

Sol. in water, alcohol and ether. 

P. Yellow or colorless thick liquid. 

Der. Obtained very largely from sugar by the lactic ferment. 
G. .-U.S.P... 75% “Aacticsacid: 


U. P. Occasionally used in the preparation of silver lactate 
positive emulsions. Acts as a preservative for slow 
chloride emulsions and prevents fog. Is a useful preserva- 
tive for amidol developer in the proportion of 5cc. lactic 
acid to 1000cc. developer. A 3% solution can be used as 
a stop bath for arresting development. 


ACID NITRIC, HNO; 
Fr. Acide Nitrique; Ger. Salpeteraure 


Syn. Aqua fortis, Hydrogen nitrate, Acid azotic. 
M. W. . 63.022 Sp:G2l42 See a 
Sol. in water and alcohol. 


P. Transparent, colorless, fuming, suffocating, caustic and 
corrosive liquid. Causes very painful burns. 


Der. 


MATERIA PHOTOGRAPHICA 15 


ea cbatcd by distillation from saltpetre and sulphuric 
aci 


U.S.P. 


U. P. Nitric acid is the principal ingredient in the nitration 


of cotton for nitrocellulose. Used as a preservative in 
pyro developer. Used in the production of silver nitrate 
and in some of the vanadium or iron toning baths. In 
process work, nitric acid is largely used as a mordant for 
etching zinc. 


ACID OXALIC, CO:.H.CO:H.2H:0 
Fr. Acide Oxalique; Ger. Oxalsaure 


Bee et 0) op. G. 1.653: “M. P. 187°C. 


Sol. 
Pr. 


Der. 


in water, alcohol and ether. 
Transparent, colorless crystals; poisonous. 


Sodium carbonate, heated under pressure with carbon 
dioxide, produces sodium formate. This heated with 
sodium carbonate, yields sodium oxalate. A calcium salt 
is added to precipitate calcium oxalate which, when 
treated with sulphuric acid, gives oxalic acid. 


GP: 


G. 
U. P. Used in the sensitizing of platinotype paper. As a 


Syn. 


preservative for pyro developer. Used for making cor- 
rections on blue prints, as it dissolves the prussian blue 
image. Used in the preparation of ferrous oxalate 
developer. With some developers oxalic acid acts as a 
restrainer. 


ACID PHOSPHORIC, H;PO, 
Fr. Acide Phosphorique; Ger. Phosphorsaure 
Ortho-phosphoric acid. 


M. W. 98.06: Sp. G. 1.750: M. P. 38.6°C. 


Sol. 
£ 
Der. 


G. 


Miscible in all proportions with water and alcohol. 
Clear, colorless, syrupy liquid. 


Obtained by oxidizing white phosphorous, first in cake 
and then with nitric acid and evaporating the solution. 


U.S.P. 85 to 88% phosphoric acid. 


U. P. A 20% solution of phosphoric acid is frequently 


employed for acidulating platinum toning baths and in 
the preparation of silver phosphate emulsions. 


16 MATERIA PHOTOGRAPHICA 


ACID PICRIC, C.H:(NO:-),;0H 
Fr. Acide Picrique; Ger. Pikrinsalpeters 


Syn. Acid picronitric, Trinitrophenol. 
MW, 8229.05 Sp Gal:/6/ aM eg) 
Sol. in water, alcohol and ether. 


P. Very poisonous and highly explosive, especially when in 
contact with metals or metallic oxides. Yellow crystals. 


Der. By the nitration of monochlorobenzol in presence of 
sulphuric acid. 


GaeU.o. 


U. P. Used in the preparation of nonhalation plates and is 
sometimes used for making color filters. 


ACID SALICYLIC, C,.H:(OH) (COOH) 
Fr. Acide Salicylique; Ger. Salicilsaure 


Syn. Acid ortho-hydroxybenzoic. 
MW, 138: Sp: G."1483 Meer 150 ee 
Sol. in alcohol and ether; Ss. in water. 
P. White crystals. 


Der. By the addition of hydrochloric acid to a solution of 
sodium salicylate, then by filtration and drying, purified 
by sublimation. 

Gi USP, 


U. P. Used as a preservative in emulsions and for the 
preservation of mounting paste. 


ACID SULPHURIC, H:.2SO, 
Fr. Acide Sulfurique; Ger. Schwefel Sdure 

Syn. Oil of vitriol. 

M. W. 98.09: Sp. G. 184: M. P. 1046°CA SBP zie 
300) C. 

Sol. in water with evolution of heat. 

P. Strongly corrosive, dense, oily, liquid; colorless when 
pure. It is intensely corrosive and chars all organic 
matter which it comes in contact with. In mixing always 


aoe the acid slowly to the water, not the water to the 
acid. 


MATERIA PHOTOGRAPHICA 17 


Der. Made by Chamber Process by roasting pyrites or sul- 
phur in specially designed furnaces, or by the catalytic 
process, the raw materials in this process being sulphur 
dioxide from pyrites, or sulphur and oxygen from the air 
to produce sulphur trioxide which is absorbed in water 
yielding sulphuric acid. The catalyzers most in use are 
spongy platinum and iron oxide. Purified by distillation. 

Cedi pea es 

U. P. Sometimes used as a preservative in pyro developer. 
Used in conjunction with nitric acid for the preparation 
of nitrocellulose. Is one of the ingredients in the various 
permanganate, persulphate, bichromate of potassium 
bleaching and reducing solutions. 


ACID SULPHUROUS, H:SO:; 
Fr. Acide Sulfureux. Ger. Schweflige Saure 


Syn. Sulphur dioxide, Sulphurous anhydride, Hydric 
sulphite. 


Nee Go sop. G. 1.025. 

Sol. in water. 

P. Colorless liquid with suffocating sulphur odor. 

Der. Pyrites are calcined and the gas absorbed in water, the 
liquor then concentrated by means of a still. 

Grobe (6% ); 

U. P. Sometimes used as a preservative for pyro developer 
and to acidify the fixing bath. It must be freshly pre- 


pared as on keeping it very quickly changes into sulphuric 
acid. 


AGAR-AGAR 
Fr. and Ger. Agar-Agar. 


Syn. Japanese gelatine, Chinese isinglass, Layor Carang. 


P. Transparent strips similar in appearance to shredded 
gelatine. 


Der. Agar-Agar is a gelatinous vegetable material made 

_ from several of the white sea weeds (gracilara lichenoides 
and eucheuma spinosum.) These sea weeds are found 
principally in the Pacific and Indian Oceans and the 
Japan Sea. 

Go U.S.P. 


18 MATERIA PHOTOGRAPHICA 


U. P. Agar-Agar has been used at different times as a 
substitute for gelatine in emulsion-making. It is, how- 
ever, more difficult to melt than gelatine and a good deal 
harder to handle. It has been used as a substitute for 
arrowroot in the preparation of silver paper. In process 
work Agar-Agar is sometimes used as a substitute for 
fish glue in the process of preparing the resist for etch- 
ing. 

ALBUMEN 
Fr. Albumine. Ger. Albumen. 


P. Almost colorless gummy liquid, which dries to a pale 
yellow solid similar looking to many of the gums. 


Der. Is an exceedingly complex organic compound and is 
obtained from blood, milk or eggs. In photography, only 
the egg albumen is used. This is prepared by separating 
the fresh white of egg from the yolk, diluting with water, 
beating to a froth, filtering and evaporating. Albumen is 
coagulated by heat at 65.5° C. It is also coagulated by 
alcohol and most inorganic salts. It is easily decomposed 
and must be used directly after preparation, otherwise a 
preservative must be added. 

G. Technical. 


U. P. Used in the preparation of albumenized paper and 
various positive processes. In process work is used as a 
substratum, and is used in conjunction with potassium 
bichromate for sensitizing zinc plates in photo etching. 
Albumen also has the property of clarifying solutions of 
gelatine. 


ALCOHOL ETHYL, C:H;OH 
Fr. Alcool Ethylique. Ger. Aethylalkohol 


Syn. Grain alcohol, Fermentation alcohol, Cologne spirits, 
Spirits of wine, Ethyl hydrate. 

M. W. 46: Sp. G. .785: M. P—1123° C2 BaP) 7342 

Sol. in water, methyl alcohol and ether. 

P. Colorless, volatile liquid, vinous odor. 

Der. Prepared by fermentation of the sugars derived from 
starch. 

G. Cologne spirits containing 95 to 96% alcohol. 

U. P. Used in the preparation of collodion and sometimes in 
the manufacture of celluloid; is frequently used as an 
addition to photographic emulsions, where it acts as a 
preservative. When present at the time of emulsification, 
has considerable influence on the formation of the silver 
halide grain, keeping it fine and uniform. 


MATERIA PHOTOGRAPHICA 19 


ALCOHOL METHYL, CH;OH 
Fr. Alcool Méthylique. Ger. Methyl Alkohol 
Syn. Wood alcohol, Wood naphtha, Methyl hydrate, Colum- 
bian Spirits. 
PeeWee pp. G. .7913: M. P—978° C.: B. P. 66.78° C. 
Sol. in water, alcohol and ether. 
P. Colorless, volatile liquid, highly poisonous. 


Der. Obtained by the destructive distillation of wood. Puri- 
fied by rectification. 


Co S.P. 

U. P. One of the solvents frequently employed in the manu- 
facture of celluloid. Is an excellent solvent for resins. Is 
sometimes used to prepare very concentrated solutions of 
developers. Used for denaturing ethyl alcohol. Its use, 


in connection with photographic emulsions, is dangerous, 
as it produces fog. 


ALUM-AMMONIA, A1:(SO,)3(NHs)250.s.24H2O 
Fr. Alun dAmmoniaque. Ger. Ammoniakalaun 
Syn. Aluminum-Ammonium sulphate. 
M. W. 906: Sp. G. 1.645: M. P. 94.5° C. 
Sol. in water; Ins. in alcohol. 
P. Colorless crystals. 


Der. Obtained by crystallization from a mixture of aluminum 
and ammonium sulphates. Purified by recrystallization. 


G. U.S.P. (Lump, ground or powdered). 


U. P. Used in the preparation of acid fixing baths and 
sometimes as a hardener for gelatine. 


ALUM CHROME, K2SO.Cr2(SO.)3.24H20 
Fr, Alun de Chrome. Ger. Chromalaun 


Syn. Chromium and potassium sulphate. 

M. W. 916. 

Sol. in water; Ins. in alcohol and ether. 

P. Violet colored crystals yielding a dichroic solution. 


Der. Obtained as a by-product in the manufacture of 
alizarine and several other dyes. 


G. Technical, crystal or powdered. 


20 MATERIA PHOTOGRAPHICA 


U. P. Chrome alum is in general use as a hardener for 
photographic emulsions, the addition being made previous 
to coating. It is also used in the preparation of the 
chrome alum fixing bath. In process work, chrome alum 
is used as a hardening agent for gelatine and fish glue, 
and is used as an addition to the nitric acid bath for etch- 
ing enamel images on zinc with a view to preventing 
the image from becoming soft. 


ALUM, IRON, AMMONIA, FeNH.(SOs,)212H2O 
Fr. Alun de fer. Ger. Ammoniakeisenalaun 
Syn. Ammonio-ferric-sulphate, Iron ammonia sulphate. 


M. W. 962. 
Sol. in water; Ins, in alcohol. 
P. Lilac or violet efflorescent crystals. 


Der. Solutions of ferric sulphate and ammonium sulphate 
are mixed, then evaporated and crystallized, purified by 
recrystallization. 


Gre U.Sira 


U. P. Has been recommended for use in fixing baths, but 
is not satisfactory. Principal use in photography is in the 
making of ferric oxalate. 


ALUM POTASH, Al:(SO,)sK250..24H2O 
Fr. Alun de Potasse. Ger. Kalialaun 
Syn. Aluminum and potassium sulphate. 


M. W. 948: Sp. G. 1.7571: M. P. 105° G 
Sol. in water; Ins. in alcohol. 
P. White crystals. 


Der. By roasting alunite in special furnaces, afterwards 
leaching the mass and recovering the salt by crystalliza- 
tion. 


Gea ate 


U. P. Used in the preparation of hardening solutions for 
fixing baths. One of the ingredients of the hypo alum 
toning bath. Can be used as a clearing bath. In process 
work used in conjunction with dilute nitric acid for 
matting surface of zinc plates previous to coating with 
bichromated albumen. Is sometimes used for hardening 
are seal emulsions, but is not so suitable as chrome 
alum 


MATERIA PHOTOGRAPHICA 21 


ALUMINU\M, Al 
Fr. and Ger. Aluminium 


Niemeyer 2s op. G 2.708: M. P. 657° C. 
Sol. in acids and alkalies; Ins. in water. 
P. Silvery ductile metal. 


Der. Obtained by electrolysis of the oxide in a bath of molten 
cryolite. 


G. Sheet and dust. 

U. P. Frequently used as one of the ingredients in flash- 
light powders. Very largely used for the construction of 
light hand cameras and for lens fittings. Used for the 
screen and plate-holders of process cameras, as it is not 
easily acted upon by silver nitrate solutions. Aluminum 
is now used as a substitute for the lithographic stone. 


ALUMINUM CHLORIDE, Al.Clc.12H:O 
Fr. Chlorure d’Alumine. Ger. Chloraluminium 


M. W. 483: M. P. 190° C. 
Sol. in water, ether and alcohol. 


P. Yellowish white crystalline or granular powder, very 
deliquescent. 


Der. Chlorine gas is passed over alumina in a heated tower, 
the product being recovered by sublimation. 
G. ‘Technical (must be kept in well stoppered bottles). 


U. P. Used in the gold and platinum toning baths. Has been 
recommended for hardening gelatine emulsions, but is 
not satisfactory. 


ALUMINUM SULPHATE, Al.(SO,)3.18H20 
Fr. Sulfate d’Alumine. Ger. Aluminiumsulfat 


Of very little importance in photography. This material 
is often erroneously called alum. 


22 MATERIA PHOTOGRAPHICA 


ALUMINUM SULPHOCYANIDE, Al (CNS); 
Fr. Sulfocyanure d’Alumine. Ger. Aluminum-rhodanid 


Syn. Aluminum sulphocyanate, aluminum-rhodanide. 
M. W. 402. 

Sol. in water; Ins. in alcohol and ether. 

P. Yellowish powder, extremely deliquescent. 


Der. Aluminum cyanide is boiled with sulphur, the product 
being purified by crystallization. 


G. C.P. (must be kept in well stoppered bottles). 


U. P. Used as a preliminary bath for self-toning papers. 
Has been recommended in connection with gold toning 
bath, but is unsatisfactory. 


AMMONIA WATER, NH.OH 
Fr. Ammonique. Ger. Ammoniakwasser 


Syn. Ammonium hydrate, ammonium hydroxide. 
Sp. Gre (238%) 897 2Be Prssor 
Sol. in water. 


P. Colorless liquid with extremely irritating fumes. Should 
be kept in a cold place in well stoppered bottles. 


Der. Gas liquor from coke and gas manufacture is distilled, 
the volatile salts and ammonia being absorbed in sulphuric 
acid. This yields ammonium sulphate, which is heated, 
the ammonia distilled off and collected in water. Also 
made from waste animal matter. 


Goel e cove: 


U. P. Used as an accelerator in pyro developer. Also for 
blackening the mercury bleached image in intensification. 
Is used as an addition to the bichromate bath for sen- 
sitizing carbon tissue. Ammonia is used in emulsion 
making in the ammonia nitrate process in order to pro- 
duce exceedingly rapid emulsions. In process work is 
used as an addition to the bichromated albumen solution 
and also the fish glue solutions. 


MATERIA PHOTOGRAPHICA 23 


AMMONIUM BICHROMATE (NH: ):Cr20O; 
Fr. Bichromate d’Ammoniaque. Ger. Ammoniumdichromat 


M. W. 252: Sp. G. 2.153. 
Sol. in water and alcohol. 


P. Yellow needles, explodes when in contact with many sub- 
stances. 


Der. Chromic acid acting on ammonium hydroxide followed 
by crystallization. 


Ge CP: 


U. P. Sometimes used for sensitizing carbon tissue, Gum 
bichromate, and in various photo-mechanical processes. 
Has greater sensitizing power than the potassium salt 
and in the carbon processes gives stronger pictures. In 
process work is used as a sensitizer for fish glue for print- 
ing half-tone images on copper and zinc. Ammonium 
bichromate is about twice as sensitive to light as is 
potassium bichromate. 


AMMONIUM BROMIDE, NH.Br. 
Fr. Bromure d’Ammonium. Ger. Bromammonium 


MW. 98: Sp: G. 2.327. 
Sol. in water, alcohol and ether. 
P. Colorless crystals. 


Der. Hydrobromic acid acting on ammonium hydroxide fol- 
lowed by crystallization. 


(see. P. granular. 


U. P. Can be used as a restrainer in place of the potassium 
salt, but must not be used with the caustic alkalies or 
carbonates, as ammonia would be set free. Largely used 
in emulsion-making, producing an emulsion with a little 
higher contrast than one made with potassium salt. 


24 MATERIA PHOTOGRAPHICA 


AMMONIUM CARBONATE, 
(NH.) HCO;+ (NH,z) (NH:) CO, 
Fr. Carbonate d’Ammoniaque. Ger. Ammoniumkarbonat 


Syn. Hartshorn, rock ammonia. 
MAW 2c 57M APSO 
Sol. in water; decomposes in hot water. 


P. Colorless crystal plates, unstable in air, rapidly becoming 
converted to the bicarbonate. 


Der. Ammonium hydroxide heated with ammonium bicar- 
bonate. 


U.S.P. (cubes or powder). 


G. 

U. P. Can be used to replace ammonia water in some 
developing solutions, but must not be dissolved in hot 
water. Is frequently used to replace ammonia in the 
ammonia processes of emulsion making. 


AMMONIUM CHLORIDE, NH:.Cl 
Fr. Chlorure d’Ammoniaque. Ger. Chlorammonium 


Syn. Sal ammoniac. 

MW. 53:5: Sp. .G.-1.520: 

Sol. in water, alcohol and ammonium hydroxide. 
P. White crystals. 


Der. Ammonia salts acting on hydrochloric acid followed 
by crystallization. 


G. U.S.P. granular. 


U. P. Used in the salting of albumenized paper, its prin- 
cipal use, however, being in the preparation of chloride 
emulsions. ~ 


AMMONIUM CITRATE, (NH:):CsH;O, 
Fr, Citrate d’Ammoniaque. Ger. Ammoniumcitrate 


Very little used in photography. Occasionally used as 
restrainer with pyro developer. 


MATERIA PHOTOGRAPHICA 25 


AMMONIUM FLUORIDE, NH.F 
Fr. Fluorure d’Ammonium. Ger. Fluorammon 


_ Very little used in photography, occasionally used for 
stripping negatives. Must be kept in wax-lined bottles. 


AMMONIUM HYPOSULPHITE, (NH).S:0s 
Fr. Hyposulphite d’Ammoniaque. Ger. Ammonthiosulfat 


Syn. Ammonium thiosulphate. 


Very little used in photography. In the earlier days was 
recommended as a substitute for the sodium salt. 


AMMONIUM IODIDE, NHI 
Fr. Iodure d’ Ammonium. Ger. Iodammon 


heyy. (145:°Sp. G. 2,501. 
Sol. in water and alcohol. 
P. White crystals. 


Der. Action of ammonium hydroxide on hydroiodic acid, fol- 
lowed by crystallization. 

Gaels f. granular. 

U. P. Is used in making iodized collodion and has been 
recommended for negative emulsions. It is unsatisfactory 
for fast gelatino-bromide emulsions because it is unstable 
and readily gives off iodine. 


AMMONIUM MOLYBDATE, (NH.)«Mo;,Ou4H:20 


Fr. Molybdate d’Ammoniaque. Ger. Molybdansaures 
Ammonium 
M. W. 1236: Sp. G. 2.38-2.95. 
Sol. in water and acids. 
P. White crystalline powder readily decomposed by heat. 


Der. By the reaction of a solution of molybdic acid and 
ammonium hydroxide followed by crystallization. 


G. U.S.P. crystals. 


U. P. Used as an ingredient in P. O. P. emulsions to give 
greater contrast; has also been recommended as an addi- 
tion to chloride and bromide emulsions to increase con- 
trast and blacks. 


26 MATERIA PHOTOGRAPHICA 


AMMONIUM NITRATE, NH.NO; 
Fr. Azotate d’Ammonium. Ger. Salpetersaures Ammon 


M. W. 80: Sp. G. 1.725: M. P. 153. Decomposes at 210° C. 
Sol. in water, alcohol and alkalies. 
P. Colorless crystals, explosive. 


Der. By the action of ammonium hydroxide on nitric acid. 
G US. Peeranilar: 


U. P. Sometimes used as a substitute for the potassium salt 
in flash-light mixtures; is one of the salts formed in 
emulsion-making by the double decomposition of ammo- 
nium bromide and silver nitrate. 


AMMONIUM OXALATE, (NH,)2C.0:H2O 
Fr, Oxalate d’Ammoniaque. Ger. Ammonoxalat 


Very little used in photography; finds occasional use in 
the preparation of ferric ammonio-oxalate. 


AMMONIUM PERSULPHATE, (NH,).S.0; 


Fr. Persulfate d’Ammoniaque. Ger. Ueberschwefelsaures 
Ammonium 
MiW. > 228: 


Sol. in water. 
P. White crystals. 


Der. By the electrolysis of a concentrated solution of 
ammonium sulphate followed by crystallization. 
GG, Prerystals: 


U. P. Its principal use is as a reducer, its valuable property 
being that it reduces the high-light detail more than the 
shadows. Has been suggested as a hypo eliminator. 
Sometimes used to remove developer stains and as an 
addition to the oxalate developer for platinotypes. Such 
an addition improves the quality of over-exposed platino- 
type prints. 


MATERIA PHOTOGRAPHICA 27 


AMMONIUM PHOSPHATE (NH.)-HPO,: 
Fr. Phosphate d’Ammonium. Ger. Ammon-phosphat 


Syn. Ammonium diphosphate, Diammonium ortho-phosphate. 

Mew. 132: Sp. G. 1.619. 

Sol. in water; Ins. in alcohol. 

P. White crystals. 

Der. Reaction of ammonium hydroxide and phosphoric acid, 
followed by crystallization. 

Cece eranylar; 

U. P. Frequently used for fire-proofing fabrics for use 
around the studio and work-rooms, and used in making 
the slow silver phosphate emulsions. 


AMMONIUM SULPHOCYANIDE, NH.CNS 
Fr, Sulfocyanure d’Ammonium. Ger. Rhodanammonium. 


Syn. Ammonium sulphocyanate, Thiocyanate or rhodanide 
of ammonia. 

eee O op. <s. 1.3057: M. P, 159°. C. 

Sol. in water and alcohol. 

P. Colorless, deliquescent crystals. Must be kept well 
stoppered. 

Der. By boiling an aqueous solution of ammonium cyanide 
with sulphur or polysulphides. 

G. Pure. 

U. P. Its principal use is in the gold toning bath for print- 
ing-out papers. A 5% solution will dissolve gelatine in 
the cold, and has therefore found some use in the develop- 
ment of over-exposed carbon prints. 


AMMONIUM SULPHYDRATE, NH:.HS 
Fr. Sulphydrate d’Ammoniaque. Ger. Schwefelammon. 


Syn. Ammonium hydrosulphide, Ammonium sulphide. 

M. W. 51: M. P. Decomposes. 

Sol. in water and alcohol. 

P. Colorless crystalline mass, rapidly turning yellow on 
exposure to air. 

Der. By passing sulphuretted hydrogen into liquor ammonia. 

G. Pure. 

U. P. Used for blackening wet collodion negatives after 


intensification with lead nitrate, copper bromide, or silver 
iodide. 


28 MATERIA PHOTOGRAPHICA 


AMMONIUM THIOMOLYBDATE, (NH,).MoS.4 
Fr. Sulfomolybdate d’Ammonium. Ger, Ammoniak 
Thiomolybdanat. 

M. W. 260. 

Sol. in water; Ins. in alcohol. 

P. Red scales. 

Der. By boiling molybdenum trisulphide in ammonium sul- 


phide. 
G. Pure. 


U. P. Used in sulphiding bromide prints in place of sodium 
sulphide. 


AMMONIUM VANADATE, NH.VO; 


Fr. Vanadate d’Ammoniaque. Ger. Vanadinsaures 
Ammoniak, 
Syn. Ammonium metavanadate. 
M. W. 116. 
Ss. in water. 
P. Colorless crystals. 
G. Pure. 


U. P. Has been used as an addition to printing-out emul- 
sions to increase contrast. 


AMYL ACETATE, C;H::C.H;:O:, 
Fr. Acétate d’Amyle. Ger. Amylacetat, Birnenol. 


Syn. Essence of jargonelle pears, Amylacetic ester, Isoamy- 
lacetate. 


M. W. 130: Sp. G. 0.8659: B. P. 148° C. 
Sol. Very slightly soluble in water; Ins. in alcohol. 
P. Colorless liquid, banana-like odor. 


Der. By adding sulphuric acid to a mixture of amyl alcohol 
and acetic acid with subsequent recovery by distillation. 


Go be 


U. P. Is used as one of the solvents in the making of 
celluloid for photographic film. When used to dissolve 
scrap celluloid, yields a hard varnish which can be applied 
cold to negatives. It has also been used in the Hefner- 
Alteneck lamp which was adopted by the International 
Congress of Photography in 1889 as a standard light in 
sensitometry. 


MATERIA PHOTOGRAPHICA 29 


ANTIMONY SULPHIDE, Sb.S; 
Fr. Sulfure d’Antimoine. Ger. Schwefelantimon. 


Syn. Antimonous sulphide, Black antimony. 
M. W. 336: Sp. G. 4.562: M. P. 546° C. 


Sol. in Ammonium sulphide, Potassium sulphide and Hydro- 
chloric acid; Ins. in water. 


P. Black crystals or Orange-red crystals; poisonous. 


Der. Occurs in nature as the black crystalline stibnite. As 
precipitated from solutions of salts of antimony, the tri- 
sulphide is an orange-red precipitate, which is filtered, 
dried and ground. 


G. Technical. 


Wer. Occasionally used in conjunction with magnesium 
powder for flashlight work, but as the products of com- 
bustion are poisonous, it is not to be recommended. 


BARIUM BROMIDE, BaBr.2H,20 
Fr. Bromure de Baryum. Ger. Baryumbromid. 
Mee Wasesoseaop. -G, 3.852. 
Sol. in water. 
P. Colorless crystals; poisonous. 


Der. By the interaction of barium sulphide and hydrobromic 
acid, with subsequent crystallization. 


G. Technical. 


U. P. Sometimes used in the preparation of collodion emul- 
sions, and has been recommended in connection with 
silver bromide emulsions as a means of increasing con- 
trast. 


BARIUM CHLORIDE, BaCl.2H.O 
Fr. Chlorure de Baryum. Ger. Baryumchlorid. 
M. W. 244: Sp. G. 3.097: M. P. 860° C. 
Sol. in water; Ins. in alcohol. 
P. Colorless flat crystals; poisonous. 


Der. By the action of hydrochloric acid on barium sulphide 
with subsequent crystallization. 


eS... 


30 MATERIA PHOTOGRAPHICA 


U. P. Occasionally used in emulsion making, both collodion 
and silver bromide. Its principal use, however, is in the 
preparation of barium sulphate by reaction with sodium 
sulphate. 


BARIUM IODIDE, BalI.2H.O 
Fr, Iodure de Baryum. Ger. Iodbaryum. 


M. W. 427: Sp. G. 5.150: M. P. Loses 2H2O at 539° C. and 
melts at 740° C. 


Sol. in water and alcohol. 


P. Colorless crystals; decomposing and reddening on 
exposure to air; poisonous. 


Der. By the action of hydriodic acid on barium hydroxide. 
G. Technical. 


U. P. Frequently used in making collodion emulsions; 
increases contrast. 


BARIUM SULPHATE, BaSO, 


Fr. Suliate de Baryum. Ger. Schwefelsaures Baryt, 
Schwerspat. 


Syn. pate Synthetic barytes, Blanc fixe, Permanent 
white, Baryta white, Mountain snow. 


M. W. 233: Sp. G. 4.476. 
Sol. in concentrated sulphuric acid; Ins. in water. 
P. Heavy white impalpable powder; poisonous. 


Der. By the action of sulphuric acid or sodium sulphate on 
solutions of barium salts followed by careful drying and 
grinding. 

G. Technical photographic. 


U. P. Principle use is in coating photographic paper to pro- 
duce a smooth, white, inert surface, upon which to coat 
the sensitive emulsions. The barium sulphate coating also 
insulates the paper stock, and prevents any reaction 
between the organic material of the paper and the emul- 
sion which might result in decomposition and fog. 
According to the surface required, various crystalline 
forms of barium sulphate are used, the two most common 
being: glossy and matte blanc fixe. Barium sulphate is 
also added to emulsions in order to produce a semi-matte 
surface. 


MATERIA PHOTOGRAPHICA 31 


BENZOL (Benzene), C.He 


Fr. Benzol, Benzine Crystallisable. Ger. Benzol, 
Steinkohlenbenzin. 


Syn. Benzol or Benzole, Coal tar naphtha, Phenyl hydride. 
any yt op Gs. 0.07843: M. P: 5.483° C.: B. P. 79.7° C. 
Sol. in alcohol and ether; Ins. in water, 


P. Clear, colorless, inflammable liquid; characteristic odor. 
Solidifies at 0° C. 


Der. (a) Illuminating gas and coke-oven gas are “scrubbed,” 
by passing through oil which thus becomes saturated with 
benzol and toluol. The resulting oil is distilled, benzol 
and toluol being recovered, which are then separated by 
fractional distillation. (b) Coal-tar, after dehydration is 
fractionally distilled, yielding “light oil.” On distilling 
this the first runnings contain the crude benzol. 

WP. 


G 

U. P. Benzol is used in the preparation of a number of 
photographic varnishes, particularly matt varnish. In 
process work benzol is largely used for dissolving India 
rubber to make the edging solution for wet collodion 
negatives, and also for coating wet plates as a pre- 
liminary to applying collodion for stripping. It is an 
excellent solvent for asphaltum, and is also used as a 
solvent in the preparation of encaustic paste. Benzol 
must not be confused with benzine which is practically 
identical with gasoline. 


CADMIUM-AMMONIUM BROMIDE, 
2CdBr.2NH.BrH2O0 
Fr. Bromure double de Cadmium et d’Ammonium. 
Ger. Zweifach-Ammonium-Cadmiumbromid. 
M. W. 758. 


Sol. in water and alcohol, and in equal parts of alcohol and 
ether. 


Der. Prepared by dissolving crystallized cadmium bromide 
and ammonium bromide in water, and then crystallizing. 


U. P. This double salt has found considerable use in collo- 
dion processes on account of its greater stability. It con- 
siderably increases the sensitiveness of the collodion 
emulsion. 


32 MATERIA PHOTOGRAPHICA 


CADMIUM-AMMONIUM IODIDE, CdI.2NH.12H.O 
Fr, Iodure double de Cadmium et d’Ammonium. 


Ger. Zweifach-Ammonium-Cadmiumiodid. 
M. W. 692. 


Sol. in water and alcohol, and in mixtures of alcohol and 
ether. 


Der. Prepared by dissolving ammonium iodide and cadmium 
iodide in water and then crystallizing. 


U. P. Used in collodion emulsion, giving considerably more 
sensitiveness than the single salts. 


CADMIUM BROMIDE, CdBr.4H:O0 
Fr. Bromure de Cadmium. Ger. Bromcadmium. 


M. W. 344: Sp. G. 5.192: M. P. 568° Civ BaP ates oe an 
Sol. in water and alcohol; Ss. in ether. 

P. Yellowish crystalline powder. 

Der. By heating cadmium to redness in bromine vapor. 

G. Technical photographic. 

U. P. Used in bromising collodion. 


CADMIUM CHLORIDE, CdCl.2H:O 
Fr, Chlorure de Cadmium. Ger. Chlorcadmium. 


M. W. 201: Sp. G. 3.327: M. P. 568° Cy Biss SG) =e 
Sol. in water and alcohol. 
P. Small white crystals 


Der. By the action of hydrochloric acid on cadmium with 
subsequent crystallization. 


G. Technical photographic. 
U. P. Sometimes used in collodion emulsions. 


MATERIA PHOTOGRAPHICA 33 


CADMIUM IODIDE Cdl, 
Fr. Iodure de Cadmium. Ger, Iodcadmium. 


ee oOo, (55.644: M: P. 385° C.:.B, P. 708°-719°. C. 
Sol. in water, alcohol and ether. 
P. Colorless, flaky crystals. 


Der. By the action of hydriodic acid on cadmium oxide and 
crystallization. 


G. Technical photographic. 


U. P. The best salt for iodizing collodion for process nega- 
tives, used in conjunction with ammonium iodide. 


CALCIUM BROMIDE, CaBr: 
Fr. Bromure de Calcium. Ger. Bromcalcium. 
Rey ee op. G. 3.c04: M. P. 680°-760° C.: B.-P. 806°- 
rat Daneel OF 
Sol. in water. 


P. White, granular, very deliquescent crystals; sharp, saline 
taste. Should be kept well stoppered. 


Der. By the action of hydobromic acid on calcium oxide, 
carbonate or hydroxide and subsequent crystallization. 


Cre tes.©. 


U. P. Used in making collodion emulsion. 


CALCIUM CARBONATE (Chalk), CaCO; 
Fr. Carbonate de Chaux. Ger. Kreide, Kohlensaures Kalk. 
M. W. 100: Sp. G. 2.72-2.95. 


Sol. in acids; Ins. in water. 

-P. White amorphous powder or colorless crystals. 

Der. By adding a soluble carbonate to a calcium salt solution. 
GaU.8.P. | 

U. P. Used in neutralizing gold toning baths. 


34 MATERIA PHOTOGRAPHICA 


CALCIUM CHLORIDE (Crystals), CaCl.6H.O 
Fr. Chlorure de Calcium. Ger. Chlorcalcium. 
M. W. 219: Sp. G. 1.654. 
Sol. in water and alcohol. 
P. White deliquescent crystals. Must be kept well stoppered. 


Der. Commercially obtained as a by-product in the Solvay 
soda process and in the manufacture of potassium 
chlorate. 


GUS 


U. P. Used occasionally in emulsion making. The commer- 
cial dry chloride (CaCl:2H2O) is used as a desiccating 
agent for platinotype and other papers. In process work 
is a constituent of the iodizer for collodion. Small circles 
of filter or blotting paper saturated with a solution of 
calcium chloride are placed in the tin cans in which film 
is packed for the tropics. 


CAMPHOR, CywHi.O 
Fr. Camphre. Ger. Kampfer. 


Syn. Formosa camphor, Japan camphor. 

M. W. 152: Sp. G. 0.986-0.996: M. P. 175° (iB) Page 
Sol. in alcohol, ether, chloroform and carbon bisulphide. 
P. White, translucent masses, easily broken. 

Der. From the wood of the camphor laurel tree. — 

G. Technical; U.S.P. 


U. P. Camphor is used in the manufacture of a number of 
photographic varnishes and retouching mediums. It is 
one of the most important constituents of celluloid, having 
a marked influence on the physical properties of the fin- 
ished material. In celluloid manufacture, camphor func- 
tions as a latent solvent, and has an influence on the life 
of the sheet and its flexibility. A number of substitutes 
for camphor have been suggested but none of them are 
quite as satisfactory as the genuine material. 


MATERIA PHOTOGRAPHICA 35 


CARBON DISULPHIDE, CS. 


Fr, Sulfure de Carbone. Ger. Schwefelkohlenstoff. 
Syn. Carbon bisulphide. 


eee sO op. -G. 1.2927: M. P:-—111.6° C.: B. P. 46:25° C. 
Sol. in alcohol and ether; Ss. in water. 


P. Clear, colorless, inflammable liquid. Care must be used 
in handling as the vapor when mixed with air forms an 
explosive compound; poisonous. 

Der. By the action of sulphur vapors on red-hot carbon, the 
vapors formed being condensed, or by heating sulphur 
and carbon in an electric furnace and condensing the 
carbon bisulphide vapors. 


G. Technical. 


U. P. Used in the preparation of various cold varnishes, as 
it is a good solvent of amber and other resins. Also 
used as a solvent for India rubber in making rubber 
solutions. 


CARBON TETRACHLORIDE, CCl, 


Syn. Tetrachloromethane. 
Rey aco op. G. 1.5835: M. P.—22.95° C.: B. P. 76.74° C. 
Sol. in alcohol and ether; Ss. in water. 


P. Light, colorless liquid, peculiar odor, yielding heavy 
vapors; non-inflammable; poisonous. 


Der. By the interaction of carbon bisulphide and chlorine 
in presence of a catalyzer. 


G. Technical. 


U. P. Is an excellent solvent of shellac, asphalt, and fats. 
Is valuable as a cleaning fluid, as it has no action on 
metals, colors or fabrics. 


36 MATERIA PHOTOGRAPHICA 


CELLULOID 
Fr. Celluloide. Ger. Celluloid. 


Sol. in alcohol and ether, and various mixtures of amyl- 
acetate, acetone, fusel oil, etc.; Ins. in water. 


Der. By mixing nitrated cellulose, camphor and _ other 
ingredients in suitable solvents, producing: what is known 
as “dope.” This is a viscous solution which is flowed upon 
a casting wheel and upon the evaporation of the solvents, 
sheet celluloid is obtained. It is produced in long rolls 
of suitable width, and in varying thicknesses, according 
to the purpose for which it is intended. Highly 
inflammable. 

U. P. Sheet celluloid is the most important flexible emul- 
sion support used in the production of modern roll film 
and motion picture film. In connection with roll film a 
suitable coating is applied on the side opposite to that 
on which the emulsion is coated to counteract the natural 
curl, producing the so-called non-curling roll film. For 
motion picture work, sheet celluloid is now produced in 
a number of different colors, to largely do away with 
tinting and toning. 


CELLULOSE ACETATE, C.H;(CO:CHs); 
Fr. Cellulose Acétate. Ger. Celluloseacetat. 


Syn. Sericose. 
Sol. in alcohol; Ins. in water. 


P. Yellowish, transparent amorphous mass. Non-inflam- 
mable. 


Der. By the acetylization of cellulose in the presence of 
sulphuric acid. 


G. Special photographic. 


U. P. Cellulose Acetate is the basis of the modern non- 
inflammable photographic and motion picture film. A 
number of forms of this material are known, their prop- 
erties varying according to the process of manufacture. 
Cellulose acetate may be obtained insoluble in alcohol, 
soluble in chloroform, etc. 


MATERIA PHOTOGRAPHICA 37 


CERIC SULPHATE, Ce(SO,).4H:O 
Fr. Sulfate de Cérium. Sulfate Cérique. Ger. Cerisulfat. 


Syn. Sulphate of cerium. 
M. W. 404. Sol. in water. 


P. Reddish-yellow crystals. 
Der. By the action of sulphuric acid on cerium carbonate. 
G. Technical. 


U. P. Is used as a photographic reducer, a 5% solution 
acting more strongly on the high-lights of a negative 
than the shadows. Is also used for sensitizing paper 
in the cerium printing processes, capable of producing 
prints in a great variety of colors according to the 
organic substances with which the prints are treated. 


CHLORAL HYDRATE, CC1: + CH(OH), 
Fr. Chloral Hydrate. Ger, Chloral Hydrat. 


Syn. Trichloradelhyde. 

peeve ype, LOL: M. P: 57° C.:; B. P..97.5° C. 
Sol. in water, alcohol and ether. 

P. ‘Transparent, colorless crystals; poisonous. 

Der. By the action of ¥% of its volume of water on chloral. 
CS USS ae 


U. P. Is sometimes used as a solvent of gelatine in the manu- 
facture of photographic mountants, and has been used 
in the preparation of non-inflammable film. 


CHLOROFORM, CHCl; 
Fr. Chloroforme. Ger. Chloroform. 


Syn. ‘Trichloromethane, Metheny] trichloride. 

M. W. 119.5: Sp. G. 1.49887: M. P.—63.2° C.: B. P. 61.20° C. 

Sol. in alcohol and ether; Ss. in water. 

P. Clear, colorless, highly refractive, volatile liquid; 
characteristic odor; non-inflammable. 

Der. By the reaction of calcium oxychloride with acetone 
and distillation. GUE SP. 


U. P. Is a solvent of amber, resins, and is useful in the 
preparation of a number of varnishes. It is also a 
good solvent for iodine, bromine, camphor, and some 
forms of cellulose acetate. Should be kept in the dark. 


38 MATERIA PHOTOGRAPHICA 


COBALT CHLORIDE, CoCl.6H.O 
Fr. Chlorure de Cobalt. Ger. Kobaltchlorid. 


Syn. Cobaltous Chloride. 

M. W.. 238: Sp. Gr184: Mo P8675 se 
Sol. in water and alcohol. 

P. Ruby-red crystals. 


Der. By the action of hydrochloric acid on cobalt oxide with 
subsequent crystallization. 


G. Technical. 


U. P. The addition of a small amount of cobalt chloride to 
printing-out emulsions increases contrast. Is one of the 
constituents of the cobalt-lead-toning bath giving a green 
image on bromide and gaslight papers. 


COPPER BROMIDE, CuBr, 
Fr. Bromure de Cuivre. Ger. Kupferbromid. 


Syn. Cupric bromide. 

MOWiZ23.5: 

Sol. in water; Ss. in alcohol. 

P. Greyish black crystalline powder. 


Der. Most easily prepared by double decomposition usirig 
solutions of copper sulphate and potassium bromide. 


Ge Ca Be 


U. P. Has been used for the intensification of negatives, and 
for bleaching bromide prints previous to sulphide toning. 
In process work the copper bromide intensifier is employed 
for half-tone negatives, and has a marked cutting action 
which tends to sharpen up the dots. Still greater density 
can be obtained by flowing over a solution of either 
sodium or ammonium sulphide. 


MATERIA PHOTOGRAPHICA 39 


COPPER CHLORIDE, CuCl. + 2H.O 
Fr, Chlorure de Cuivre. Ger. Kupferchlorid. 


Syn. Cupric chloride, Copper bi- or di-chloride. 
Maw. 1/0:5: Sp..G. 2.47. 
Sol. in water, alcohol and ether. 


P. Greenish-blue, deliquescent crystals; poisonous. Must be 
kept well stoppered. : 


Der. Copper carbonate is dissociated with hydrochloric acid 
and the product is crystallized. 


G. Pure crystals. 


U. P. Is occasionally used as a reducer according to Spiller’s 
formula. Added to printing-out emulsions it increases 
contrast. Is also used in Obernetter’s photogravure 
process. A small amount of a 1% solution of copper 
chloride added to silver bromide emulsion reduces the 
speed and increases contrast. 


COPPER SULPHATE, CuSO. + 5H:0 
Fr. Sulfate de Cuivre. Ger. Kupfersulfat. 


Syn. Cupric sulphate, Blue vitriol. 
M. W. 249.5: Sp. G. 2.284. 
Sol. in water and alcohol. 


P. Blue crystals, slowly efflorescing in air; almost white 
when dehydrated; poisonous. Should be kept well 
stoppered. 


Der. By the action of sulphuric acid on copper or copper 
oxide in large quantities, with evaporation and crystalliza- 
tion. 


Ge U:S.P. 


U. P. With an excess of liquor ammonia gives a blue solu- 
tion which forms a useful filter for color sensitometry 
and three color work. Is one of the constituents of the 
bromo-iodide of copper intensifying solution, and is used 
in copper toning baths producing various tones from warm 
black to red chalk upon bromide prints. In process work 
is used as an addition to the wet plate developer, its 
function being to retard the oxidation of the ferrous 
sulphate; in electrotyping it is used with sulphuric acid 
to form the depositing solution. 


40 MATERIA PHOTOGRAPHICA 


ETHER, C.H;OC2H;s 
Fr. Ether Sulfurique. Ger. Aether. 


Syn. Ethyl oxide, Ethylic ether, Sulphuric ether. 

M. W. 74: Sp. G. 0.71994: M, P.—116,2° C.: B. P. 34.97° C. 

Sol. in water and alcohol. 

P. Very light, transparent, colorless, volatile, exceedingly 
inflammable, mobile liquid; pleasant aromatic odor. 
Note: Have no flames or sparking electrical equipment 
present when ether is being used. Should be kept well 
stoppered in a cool place. 

Der. By the action of sulphuric acid on ethyl alcohol, fol- 
lowed by distillation. ; 

Ge AS. P3 

U. P. Used in the preparation of collodion and varnishes, 
also for washing bitumen to increase its sensitiveness, 
and with alcohol as a solvent for bitumen in a process 
for graining the plate by reticulation. Is a solvent for 
certain forms of cellulose acetate. Is also a solvent of 
iodine, bromine, sulphur, phosphorus, many essential oils, 
corrosive sublimate and other salts. 


FERRIC AMMONIO-CITRATE (Brown), 
4Fe CeHsO73 (NH,) sCeHsO73 Fe ( OH); 


Fr. Citrate de fer Ammoniacale. Ger. Braune Citronensaure 
Eisenoxydammoniak. 


Syn. Ammonium citrate of iron. 

M. W. 2030. 

Sol. in water; Ins. in alcohol. 

P. Reddish-brown, transparent, hygroscopic crystalline 
scales; saline taste; deliquescent in moist air. Should be 
kept well stoppered and in the dark. 

Der. By the addition of citric acid to ferric hydroxide, then 
adding ammonium hydroxide, followed by filtration. 

Ge US.P: 

U. P. Used in conjunction with potassium ferricyanide in 
the iron printing processes. There is also a green salt 
which gives more sensitive papers with ‘cleaner whites 
than the brown salt. 


MATERIA PHOTOGRAPHICA 41 


FERRIC AMMONIO-OXALATE, 
Fe2(C20,) 33(N H,)2C20.8H2O0 


Fr. Oxalate Ammoniaco-Ferrique. Ger. Ammonium 
Ferrioxalat. 


Syn. Ammonium oxalate of iron, Oxalate of iron and 
ammonia. 


M. W. 892. 
Sol. in water. 
P. Green crystals. 


Der. By the interaction of ammonium binoxalate and ferric 
hydroxide. 


G. Technical. 


U. P. Sometimes used in the preparation of blue prints. 
Also used in the cold development of platinum and print- 
out platinum processes. 


FERRIC AMMONIO-SULPHATE, 
FeSO.(NH:z)250.6H:2O 


Fr. Sulfate de fer Ammoniacale. Ger. Schwefelsaure. 
Eisenoxydammoniak. 
Syn. Ammonium sulphate of iron. 
M. W. 328. 
Sol. in water; Ins. in alcohol. 
P. Pale greenish crystals. 


Der. By mixing solutions of ferric sulphate and ammonium 
sulphate, followed by evaporation and crystallization. 


Sr aoeP. 

U. P. Is occasionally used as a substitute for ferrous sul- 
phate on account of its greater stability, and has been 
used in the developing of wet plates. 


42 MATERIA PHOTOGRAPHICA 


FERRIC CHLORIDE (Lump), FeCl,6H.O0 
Fr. Chlorure Ferrique. Ger. Eisenchlorid. 


Syn. Perchloride or sesquichloride of iron, Iron trichloride. 
MW s270.5e 0M Pe 37 ate 

Sol. in water, alcohol and ether. 

P. Very deliquescent, orange-yellow, crystals (lumps). 
Der. By passing chlorine into a solution of ferrous chloride. 
G. 20823 


U. P. Is sometimes used as a reducer for negatives, but is 
not to be recommended as it is likely to produce yellow 
stains, due to formation of basic ferrous salts. In process 
work is used as a mordant in photogravure and half-tone 
plates. 


FERRIC OXALATE, Fe:2(C:0.)s 
Fr. Oxalate Ferrique. Ger. Ferrioxalat. 


Syn. Iron sesquioxalate. 

M. W. 376. 

Sol. in water; Ins. in alcohol, 

P. Greenish glistening scales. Extremely sensitive to light. 


Der. A solution of ammonia-iron-alum and liquor ammonia 
mixed together and allowed to stand until the precipitated 
ferric hydrate has settled, then pure oxalic acid is added 
and the mixture allowed to stand in the dark until the 
precipitate is completely dissolved. 


G. Technical. 


U. P. Used in the Kallitype process, its chief use, however, 
is as the sensitive salt in the platinotype process. 


MATERIA PHOTOGRAPHICA 43 


FERRIC SODIUM OXALATE, - 
Fe (C204)33Naz C2041 1H.O 
Fr. Oxalate de fer et de Soude. Ger. Natriumferrioxalat. 
Syn. Sodio-ferric oxalate. 
M. W. 976. 
Sol. in water; Ins. in alcohol. 
P. Emerald-green crystals. 


Der. By the interaction of sodium acid oxalate and ferric 
hydroxide. 


G. Technical photographic, 


U. P. Used in the preparation of printing-out platinum 
papers. 


FERRIC SULPHATE, Fe.(SO:);9H:O 


Fr. Sulfate Ferrique. Ger. Ferrisulfat, Schwefelsaure. 
Fisenoxyd. 

Syn. Sesqui-sulphate of iron. 

M. W. 563: Sp. G. 2-2.1: M. P. Decomposes. 

Sol. in water. 

P. Greenish crystals. 

Der. By adding sulphuric acid to a solution of ferrous sul- 
phate. 

iG a1.5.P. 

U. P. Has been suggested as a reducer, but is very likely to 
give yellow stains, due to the formation of basic iron 
salts in the film. 


FERROUS NITRATE, Fe(NO:;)218H20 
Fr. Azotate Ferreux. Ger. Salpetersaure Eisenoxydul. 


Syn. Protonitrate of iron. 

M. W. 536. 

Sol. in water and in dilute alcohol. 

P. Greenish-white crystals. 

Der. Prepared by mixing ferrous sulphate with barium 
nitrate in solution. 


U. P. Used in wet collodion process, gives an image much 
whiter in color than ferrous sulphate. 


44 MATERIA PHOTOGRAPHICA 


FERROUS POTASSIUM OXALATE, 
K.2Fe(C204)2H2O 
Fr. Oxalate de Potassium Ferreux. Ger. Kalium-Eisenoxalat. 


Syn. Potassio-ferrous Oxalate. 
M. W. 328. 
Sol. in water. 


Der. Occurs in the ferrous oxalate developer by ie mixture 
of ferrous sulphate and potassium oxalate. 


U. P. The ferrous oxalate developer is one of the oldest for 
plates and bromide papers, and has almost entirely been 
replaced by the modern organic developers. Its 
advantage is the production of an image in pure metallic 
silver, that is to say, without stain. When used for 
bromide papers, an acid bath after development is nec- 
essary in order to prevent the deposition of basic iron 
salts in the paper. Bromide acts as a restrainer and 
small quantities of hypo solution acts as an accelerator 
with this developer. Can also be used as the blackening 
solution in connection with intensifying with mercuric 
chloride and allows of repeating the bleaching and black- 
ening processes. 


FERROUS SULPHATE, FeSO.7H:O 
Fr. Sulfate de Fer. Ger. Schwefelsaures Eisenoxydul, 


Syn. Sulphate or protosulphate of iron, Green copperas, 
Green Vitriol. 


M. W. 278: Sp. G. 1.8987: M. P. 64° C. 
Sol. in water; Ins. in alcohol. 


P. Greenish crystals, often rusty in color from oxidation and 
efforesence. Before use the rusty powder should be 
rinsed off. 


Der. (a) A by-product from the pickling of steel. (b) By 
the action of dilute sulphuric acid on iron and with sub- 
sequent crystallization. 

23 5 Cha o 

U. P. Is used as a developer for wet collodion plates, and 


is one of the ingredients used in the preparation of the 
ferrous oxalate developer. 


MATERIA PHOTOGRAPHICA 45 


FORMALIN, CH:O 
Fr. Formol. Ger. Aldehyde Formique. 


Syn. Formaldehyde, Formic aldehyde. 
Sp. G.  1.075-1.081. 
Sol. in water and alcohol. 


P. Clear, colorless liquid. Suffocating odor; poisonous. Is 
an aqueous solution of formaldehyde gas. ‘The vapors 
attack the mucous membrane of the eyes, nose and throat, 
causing intense irritation. 


Der. The vapors of methyl alcohol are passed through a 
heated copper tube and subsequently absorbed in water. 


G. U.S.P. 40%. 


U. P. Is used as a hardening bath immediately after fixing 
for both negatives and prints, a suitable strength is 10%. 
Used in conjunction with the hydroquinone developer 
yields negatives of great contrast. In emulsion work is 
used as a hardener; very small amount considerably 
raises the melting point of gelatine; emulsions hardened 
with formaldehyde stand warm developing solutions 
exceptionally well. 


GELATINE 
Fr. Gelatine. Ger. Gallerte, Gelatin. 


Sol. in hot water; Ins. in alcohol and ether, also Ins. in 
cold water but will absorb it and swell up to a slimy 
mass. 

P. Translucent sheets or flakes. 


Der. By extraction with water from certain kinds of bones 
and parts of the skin of cattle, selected, washed and . 
treated with especial care so that the resulting product is 
cleaner and purer than ordinary glue. The raw stock for 
photographic gelatines must be carefully chosen, as it 
has a decided influence on the characteristics and 
behavior of the finished product. 


G. Photographic, Hard, Medium, Soft. 


U. P. Gelatine is used in the preparation of baryta coating 
solutions for photographic paper, in collotype, photo- 
gravure, and many other photo-mechanical processes. It 
is the chief ingredient in photographic mountants. Solu- 
tions of sulphocyanide and barium chloride dissolve 
gelatine in the cold, and so do acetic, oxalic, hydrochloric 
and sulphuric acids. Gelatine is the principle factor in 
modern emulsion making, acting as the supporting colloid 


46 MATERIA PHOTOGRAPHICA 


for silver iodide, bromide or chloride. For emulsion 
making it is nearly always necessary to use a proper 
blend or selection of hard and soft gelatines in order to 
secure the desired photographic quality. In process work 
gelatine has many uses: in the preparation of photo- 
lithographic paper, carbon tissue, gelatine reliefs, sub- 
stratum on glass plates or films, litho-transfer papers 
and stripping negative films, also used in making color 
filters and for glazing prints. 


GLYCERINE, C;:H;(OH)s; 
Fr. Glycérine. Ger. Glyzerin. 
M. W. 92:.Sp. G. 1.2604: M. P. 17° CB Pe zea 


Sol. in water and alcohol; Ins. in ether. 

P. Clear, colorless, or pale yellow, odorless, syrupy euids 
sweet, warm taste. 

Der. From the spent lye liquor from the saponification of 
fats and oils in the soap industry, by the precipitation of 
salt, albuminoids and metallic soaps of the higher fatty 
acids, by iron persulphate (crude) or aluminum sulphate 
and concentration with subsequent steam distillation. 

Cour oie 

U. P. Glycerine is used as a control in developing platino- 
types, and is frequently used as an addition to emulsions 
to insure a smooth coating and to prevent curling. In 
motion picture work, film is immersed in a glycerine bath 
to keep it flexible and supple. In collotype, glycerine is 
used for etching or damping the plate previous to inking. 


GOLD CHLORIDE (Yellow), AuCl; 
Fr. Chlorure d’or. -Ger. Goldchlorid. 


Syn. Trichloride or perchloride of gold, Auric chloride. 

M. W. 303. 

Sol. in water, alcohol and ether. 

P. Yellowish brown crystals. Very hygroscopic, should be 
kept in solution. 

Der. By dissolving gold in aqua regia. 

G. Photographic. 

U. P. Principal use, in toning baths for gelatino-chloride 
and collodio-chloride printing-out papers. In some of 
the so-called self-toning papers gold chloride is added 
to the emulsion. 


MATERIA PHOTOGRAPHICA 47 


HYDRAZINE, NH.NH, 
Fr. Hydrazine. Ger. Hydrazin. 
Syn. Diamidogen or Diamine. 
ames. 3p. Gr. 1.013: M. P, 1.4° C.: B. P. 113,5° C. 
Sol. in water and alcohol. 
P. Colorless liquid. 


Der. By reduction of nitrosamine with zinc dust and acetic 
acid. 


G. Special photographic. 


U. P. Several hydrazine compounds have been used as 
additions to emulsions to obtain more contrast, and are 
said to increase the latitude of an emulsion, making it 
difficult to over-expose. . 


HYDROGEN PEROXIDE, H.O: 
Fr. Péroxyde d’Hydrogéne, Fau Oxygénée. 
Ger. Wasserstoffperoxyd. 
Syn. Hydrogen dioxide, Hydroxyl, Perhydrol. 
M. W. 34: Sp. G. 1.111. 
Sol. in water, alcohol and ether. 


P. Colorless, heavy liquid, appearing in commerce in the 
form of an aqueous solution. Keep cool and dark. A 
powerful oxidizing agent. 


Der. By the action of dilute mineral acid, usually sulphuric 
on barium peroxide. 


G. U.S.P.; 30% by weight. 


U. P. Has been suggested as a “hypo” eliminator; when 
rendered alkaline is a weak developer. The fact that 
wood, resins, etc., act upon dry plates has been ascribed 
to the presence of hydrogen peroxide. Recent investiga- 
tions have shown that hydrogen peroxide can produce 
upon the photographic emulsion an effect equivalent to 
light action. 


48 MATERIA PHOTOGRAPHICA 


LEAD ACETATE, Pb(CH;:COO).3H:O 
Fr. Acetate de Plomb. Ger. Bleiacetat. 


Syn. Sugar of lead, Normal plumbic acetate. 

MW 370 -sSn 4G: 2.50: M. P. Loses 3H,0 atv Seat eee 
280° 3. 

Sol. in water; Ins. in alcohol. 

P. White crystals (Commercial grades are frequently brown 
or gray lumps); poisonous. 

Der. By the action of acetic acid on litharge. 

G..- USP; 


U. P. Used in some forms of combined toning and fixing 
baths. 


LEAD CHROMATE, PbCrO, 
Fr. Chromate de Plomb. Ger. Chromsaures Blei. 


M. W. 323: Sp. G. 6.123: M. P. Decomposes at 600° C. 
Sol. in acids; Ins. in water. 
P. Yellow crystals; poisonous. 


Der. By interaction of solutions of sodium chromate and 
lead nitrate. 

G. ‘Technical. 

U. P. Is used as a pigment, and in the preparation of orange | 
fabric for dark room illumination. A useful orange safe- 
light may be prepared by bathing a fixed-out plate for 
several minutes in a 5% potassium chromate solution, 
rinsing and then immersing in lead acetate solution, 
washing and drying. 


LEAD NITRATE, Pb(NOs): 
Fr. Azotate de Plomb. Ger. Bleinitrat. 
M. 48. 2381? ae: G. 4.53: M. P. Decomposes between 205° 
and 2e3206) 
Sol. in water nie alcohol. 


P. White crystals; promotes combustion in contact with 
organic matter; poisonous. 


- Der. By the action of nitric acid on lead. 


Ge AU Ly 


U. P. Used in the lead intensifier and in some combined 
‘toning and fixing baths. 


MATERIA PHOTOGRAPHICA 49 


LITHIUM BROMIDE, LiBr 
Fr. Bromure de Lithium. Ger. Bromlithium. 
Bie Wwe or. op. G: 3466: M. P, 442°-547° C. 


Sol. in water, alcohol and ether. 


P. White crystals. Very deliquescent, must be kept in well 
stoppered bottles. 


Der. By the action of hydrobromic acid on lithium 
hydroxide with subsequent crystallization. 


S. US.P: 


U. P. On account of its solubility in ether and alcohol, it is 
used in collodion emulsion making. 


LITHIUM CHLORIDE, LiCl 
Fr. Chlorure de Lithium. Ger. Chlorlithium. 


Mi W. 42.5: Sp. G. 1.998-2.074: M. P. 602° C. 

Sol. in water, alcohol and ether. 

P. White crystals. 

Der. By the action of hydrochloric acid on lithium hydroxide 
with subsequent crystallization. 

G. Technical granular. 


U. P. Used in collodio-chloride printing-out emulsions; has 
been recommended as a constituent of gelatino-chloride 
emulsions to increase contrast. 


MAGNESIUM BROMIDE, MgBr.6H:0 
Fr. Bromure de Magnésium. Ger, Brommagnesium. 


M. W. 291: M. P. Decomposes. 

Sol. in water; Ss. in alcohol. 

P. Colorless, very deliquescent crystals; bitter taste. 

Der. By the action of hydrobromic acid on magnesium oxide 
with subsequent crystallization. 

G. Technical granular. 

U. P. Is used in collodion emulsion making, and has been 
recommended in connection with gelatino-bromide emul- 
sions to increase contrast. 


50 MATERIA PHOTOGRAPHICA 


MAGNESIUM CARBONATE, MgCoO; 
Fr. Carbonate de Magnésium. Ger. Kohlensaures Magnesium. 
M. W. 84: Sp. G. 3.04: M. P. Decomposes at 350° C. 
Sol. in acids; Ins. in water. 


P. Very light, white powder, consisting of a mixture of 
crystals and amorphous particles. 


Der. Found as such in nature. 

(Ss See 

U. P. In process work it is used by photo-engravers for rub- 
bing into the hollows of an etched plate so that the 


progress of etching may be seen; and in the form of a 
fine powder is used in the dry enamel process. 


MAGNESIUM CHLORIDE, MgCl.6H:O 
' Fr. Chlorure de Magnésium. Ger. Chlormagnesium. 
M. W. 202: Sp. G. 1.569. M. P. Loses 2H:0 at 100° CC. Bor: 
Decomposes. 
Sol. in water and alcohol. 
P. Colorless or white crystals. 
Der. By the action of hydrochloric acid on magnesium oxide. 
Deliquescent and must be kept in well stoppered bottles. 
G. Fused. 
U. P. Has been suggested as a fixing agent, but is not as 


powerful as “hypo.” Is occasionally used in collodion 
emulsion making. . 


MERCURY CHLORIDE (Mercuric), HgCl. 
Fr. Bichlorure de Mercure. Ger. Quecksilberchlorid. 
Syn. Perchloride or Bichloride of mercury, Corrosive subli- 
mate. 
M. W.. 271: Sp. G, 5.32: Mo PO2652 "ae ee 
Sol. in water, alcohol, ether, pyridine and acetic acid ester. 
P. White crystals; very poisonous. Should be kept in the 
dark. 
Der. By subliming common salt and mercuric sulphate. 


Gig o; ks 


U. P. Used as the bleaching agent in mercurial intensifica- 
tion. Used in small amounts in connection with the hypo 
alum bath, produces colder sepia tones. 


MATERIA PHOTOGRAPHICA 51 


MERCURY IODIDE (Mercuric), HglI. 
Fr. Iodure de Mercure. Ger. Quecksilberiodid. 


Syn. Red iodide of mercury, Biniodide of mercury. 
Beeston, CG, 6.2-0.62: M. P, 241°-257° C.: B.. P. 
349° C, 


Sol. in sodium thiosulphate or potassium iodide solutions; 
Ins. in water. 


P. A scarlet-red, amorphous powder; poisonous. 


Der. Precipitated from mercuric chloride solution by potas- 
sium ‘iodide. 
Cae GES A a 


U. P. Is used in intensification, and is usually prepared 
direct by the reaction of mercuric chloride and potassium 
iodide. 


MERCURY SULPHOCYANIDE, Heg(SCN): 
Fr. Sulfocyanure de Mercure. Ger. Rhodanquecksilber. 


Syn. Mercuric sulphocyanate and Rhodanide. 
M. W. 316: M. P. Decomposes. 

Sol. in alcohol; Ss. in water. 

P. White powder; poisonous; explosive. 


Der. By precipitation of mercuric nitrate with ammonium 
sulphocyanate and subsequent solution in a large amount 
of hot water and crystallizing. 


G. Technical. 


U. P. Usually prepared in solution by the reaction of 
mercuric chloride and potassium sulphocyanide. Is a good 
intensifier for negatives, giving a good black image. Fur- 
ther intensification can be obtained by afterwards apply- 
ing a developer. 


52 MATERIA PHOTOGRAPHICA 


POTASSIUM BICHROMATE, K:.Cr.O, 


Fr. Bichromate de Potasse. Ger. Kaliumbichromat, 
Saures Rotes, Chromsaures Kalium. 


Syn. Potash or potassium dichromate; Acid or red potas- 
sium chromate. 

M. W. 294: Sp. G. 2.692: M. P. 396° C.: B. P. Decomposes 
at 5007, C: 

Sol. in water; Ins, in alcohol and ether. 

P. Bright, yellowish-red, transparent crystals; bitter, metallic 
taste; poisonous. 

Der. By heating an aqueous solution of sodium bichromate 
with potassium chloride, concentrating the solution, where- 
upon sodium chloride is deposited in the vessel. Lead 
rods are suspended in the solution and the bichromate 
crystallizes on these. 


Cs ek 


U. P. Used in the carbon process, and many photo- 
mechanical processes, as it has the property of rendering 
gelatine, fish glue and other colloids insoluble after they 
have been acted upon by light. Is also used for sensitiz- 
ing photo-lithographic paper, collotype plates and the 
albumen coating for zinc. Is used in conjunction with 
sulphuric acid as a glass and bottle cleaning fluid. 


POTASSIUM BROMIDE, KBr 
Fr. Bromure de Potasse. Ger. Bromkalium. 


Syn. Bromide of potassium or Potash. 
M. W. 119: Sp. G. 2.749: M. P. 730° GB 
Sol. in water; Ss. in alcohol and ether. 


P, White crystalline granules or powder; pungent, strong, 
bitter saline taste; somewhat hygroscopic. 

Der. Potassium hydroxide in hot solution is treated with 
bromine, the solution evaporated to dryness, the residue 
mixed with carbon and heated to redness. 

US. 


G 

U. P. Its principal use is in the manufacture of gelatino- 
bromide emulsions. It also acts as a_ restrainer in 
development, and is most active with pyro, hydroquinone, 
and para-amidophenol. In process work it is used in 
making up the copper bromide intensifying solution for 
wet plate negatives. 


MATERIA PHOTOGRAPHICA 53 


POTASSIUM CARBONATE, K:;CO; 


Fr. Carbonate de Potasse. Ger. Pottasche, Kohlensaures 
Kalium. 


Syn. Potash, Pearlash, Subcarbonate of potash, Salt of 
tartar, Salt of wormwood. 


BOW de> op. G. 2.3312: M. P. 909° C.: B. P. Volatile at 
white heat. 


Sol. in water; Ins. in alcohol and ether. 

P. White, deliquescent, granular powder; alkaline reaction. 
Der. Obtained from wood ashes. 

GUS. P. 


U. P. Used as an accelerator in development. 


POTASSIUM CHLORATE, KCIO; 
Fr. Chlorate de Potasse. Ger. Chlorsaures Kalium. 


Syn. Chlorate of potash. 


Beye. op. G. 2.337: M. P. 357° C.: B. P. Decomposes 
at about 400° C., giving off oxygen. 


Sol. in water and alkalis; Ss. in alcohol. 


P. Transparent, colorless crystals or white powder; cooling 
saline taste; poisonous; must not be ground with sugar, 
sulphur or other combustible substances, may cause 
explosions. 


Der. By electrolyzing a hot poucca trated alkaline solution 
of potassium chloride. 


EO RSS ae 


U. P. Sometimes used in the sensitizer for platinotype paper 
to give brilliancy to the image. Its principal use, how- 
ever, being in flashlight mixtures. In process work, is 
used with hydrochloric acid as an etching solution for 
copper and steel, known as the Dutch mordant. 


54 MATERIA PHOTOGRAPHICA 


POTASSIUM CHLORIDE, KCl 
Fr. Chlorure de Potasse. Ger. Chlorkalium. 
M. W. 74.5: Sp. G. 1.987: M. P. 772° C.: B. P. Decomposes 
at about 400° C. 


Sol. in water and alkalis; Ss. in alcohol; Ins. in absolute 
alcohol. 


P. Colorless or white crystals or powder; strong saline taste. 


Der. Prepared by neutralizing hydrochloric acid with potas- 
sium carbonate. 


G. Granular. 
U. P. Used in emulsion making. 


POTASSIUM CHLOROPLATINITE, K:,PtCh 


Fr. Chloroplatinite de Potassium. 
Ger. Platinchloruskalium. 
Syn. Chloroplatinite or platinochloride of potash. 
M. W. 413.4: Sp. G. 3.291. 
Sol. in water; Ins. in alcohol. 
P. Ruby-red, deliquescent crystals. 


Der. By adding potassium carbonate to a solution of chloro- 
platinous acid. 


G. Special photographic. 


U. P. Used in the platinotype process and as one of the 
ingredients of toning baths for silver prints. 


POTASSIUM CHROMATE, K.CrO, 
Fr. Chromate de Potasse. Ger. Chromsaures Kalium. 


Syn. Neutral or yellowish chromate of potash. 
M. W. ='194: Sp."G. 273198] MSs e/a 
Sol. in water; Ins. in alcohol. 

P. Yellow crystals. 


Der. By adding potassium carbonate to a solution of potas- 
sium bichromate and crystallizing. 


G. Technical. 


U. P. Sometimes used as a liquid light filter in sensitometry 
or three-color work. In process work, the chromate has 
been used as a sensitizer in place of bichromates, but is 
not as satisfactory. 


MATERIA PHOTOGRAPHICA 55 


POTASSIUM CITRATE, K;C;.H;O,;,H.O 
Fr. Citrate de Potasse. Ger. Citronensaures Kalium. 


Syn. Tribasic citrate of potash. 


M. W. 342: Sp. G. 1.98: M. P. Decomposes when heated to 
about 230° C. 


Sol. in water and alcohol. 


P. Colorless or white crystals or powder; extremely deli- 
quescent. 


Der. By the action of citric acid on potassium carbonate. 
GPiU.S-P. 


U. P. Is used as a restrainer in alkaline development, and 
in several of the copper toning baths. Because of its 
deliquescent nature it is best to prepare this salt in solu- 
tion; the stronger the solution, the better it will keep; 
dilute solutions very soon grow a fungus. 


POTASSIUM CYANIDE, KCN 
Fr, Cyanure de Potassium. Ger, Cyankalium. 


Syn. Cyanide of potash, Cyanide. 


M. W. 65: Sp. G. 1.52: M. P. At red-heat.: B. P. At red- 
heat. 


Sol. in water, alcohol and glycerin. 


P. White, amorphous, deliquescent lumps or crystalline 
mass; faint odor of bitter almonds; extremely poisonous, 
do not handle with bare hands! 


Der. Prepared by fusing potassium ferrocyanide with potas- 
sium carbonate in an iron crucible. 


G. Pure granulated. 


U. P. Used as a fixing agent in collodion processes and 
sometimes as a clearing agent for bromide prints, also 
used in Monckhoven’s intensifier. In process work, is used 
for fixing wet collodion negatives and for cutting or 
reducing solution. Is also used in connection with electro- 
deposition and for degreasing articles previous to plating. 


56 MATERIA PHOTOGRAPHICA 


POTASSIUM FERRIC OXALATE, 
Fe(C:0,)3sK33H:0 
Fr. Oxalate Potassico-Ferrique. Ger Kalium-Ferri-Oxalat. 


M. W. 491. 

Sol. in water; Ins. in alcohol. 

P. Bright green crystals. 
Der. By acidulating potassium ferrous oxalate and exposing 


to light. 3 
U. P. Used in Belitski’s reducer and in several iron printing 
processes. 


POTASSIUM FERRICYANIDE, K;Fe(CN),. 
Fr. Cyanoferride de Potassium. Ger, Ferrid-Cyan-Kalium. 


Syn. Ferricyanide of potash, Red prussiate of potash. 
M. W. 329: Sp. G. 1.8109: M. P. Decomposes when heated. 
Sol. in water; Ss. in alcohol. 


P. Bright-red, lustrous crystals, the crystals often become 
coated with a yellowish powder, this powder should be 
washed off before using. Poisonous. 


Der. Chlorine is passed into a solution of potassium ferro- 
cyanide, the ferricyanide separating out. 


G. Pure crystals. 


U. P. Used in several iron printing processes, but its prin- 
cipal use is in conjunction with hypo, forming Farmer’s 
reducer. In conjunction with potassium bromide is used 
for: bleaching bromide or gaslight prints previous to 
sulphiding. In process work, is one of the ingredients of 
the lead nitrate intensifier. 


MATERIA PHOTOGRAPHICA 57 


POTASSIUM FERROCYANIDE, K.:Fe(CN).3H:O 
Fr. Cyanoferrure de Potassium. Ger. Ferrocyankalium. 


Syn. Ferrocyanide of potash, Yellow prussiate of potash. 


M. W. 422: M. P. Loses its water of crystallization when 
sees to 60° C.: B. P. Decomposes when heated to red- 
eat. 


Sol. in water; Ins. in alcohol, 


P. Lemon-yellow crystals or powder; effloresces on exposure 
tO air. 


Der. Obtained by fusing potassium carbonate with horn 
clippings, and stirring with an iron agitator. 


reer. 


U. P. Used as a developer in some iron printing processes. 
The addition of a small amount to pyro and hydro- 
quinone developers has been recommended as a means 
of lowering fog and giving greater density. A weak solu- 
tion is used as one of the test reagents for identifying 
iron and other metallic spots in paper raw stock. 


POTASSIUM FLUORIDE, KF2H:0 
Fr. Fluorure de Potassium. Ger. Fluorkalium. 


Mew. 94> M.-P. 41° C. 
Sol. in water and hydrofluoric acid; Ins. in alcohol. 
P. White crystalline, deliquescent powder; sharp saline taste. 


Der. By saturation of hydrofluoric acid with potassium car- 
bonate. 


G. Technical. 


U. P. Used for stripping films from glass negatives. A 
five-minute immersion in a 2% solution with subsequent 
immersion in a 2% solution of sulphuric acid is sufficient. 
It keeps better than hydrofluoric acid and does not as 
strongly attack the skin, lungs or mucous membranes. 


58 MATERIA PHOTOGRAPHICA 


POTASSIUM HYDRATE, KOH 
Fr. Potasse Caustique. Ger. Aetzkali. 


Syn. Caustic potash, Potassium hydroxide. 

M. W. 56: Sp. G. 2.044: M. P. 360.4° C.: B.°P. Sublimes 
when heated above melting point. 

Sol. in water and alcohol; Ss. in ether. 

P. White, deliquescent lumps or sticks. It readily attacks 
corks and glass stoppers, these should be waxed or 
paraffined. Must not be handled, as it is a very powerful 
escharotic inflicting severe burns upon the _ skin; 


poisonous. 
Der. Obtained by decomposing potassium carbonate with milk 
of lime. Gee 


U. P. Used as an accelerator in alkaline development. In 
process work, crude caustic potash is used for cleaning 
old negative glasses, and for taking the ink and resist 
off copper and zinc plates after etching. It is also used 
for cleaning articles previous to electro-plating. 


POTASSIUM IODIDE, KI 
Fr. Iodure de Potassium. Ger. Iodkali. 


Syn. Iodide of potash. 
M. W. 166: Sp. G. 3.123: M. P. 680° CS BSP i4z0 
Sol. in water, alcohol and ether. 


P. White crystals, granules or powder; strong bitter saline 
taste. 


Der. A hot solution of potassium hydroxide is treated with 
iodine, evaporated to dryness, mixed with carbon and 
heated to redness. G. US 


U. P. Used in the preparation of the mercuric iodide 
intensifier. Used in emulsion making, particularly in 
conjunction with gelatino-bromide emulsions; has the 
property of reducing emulsion fog, increasing contrast, 
and giving increased density. The use of more than a 
small percentage, however, yields an emulsion which is 
slow in fixing. It is generally conceded that a complex 
double salt of bromo-iodide of silver is formed and is 
responsible for the particular character and photographic 
quality of bromo-iodide emulsions. A very small amount 
of a 1% solution added to a finished emulsion, enormously 
decreases its speed. Is also used in some of the more 
modern dye mordanting processes. 


MATERIA PHOTOGRAPHICA | 59 


POTASSIUM METABISULPHITE, K.S.0O; 
Fr. Métabisulfite de Potassium. Ger, Kaliummetabisulfit. 
Syn. Metabisulphite of potash, Potassium pyrosulphite. 
M. W. 222. 
Ss. in water; Ins. in alcohol. 


P. Clear, transparent crystals; smelling of sulphurous acid 
gas. 


Der. By heating potassium bisulphite until it loses water. 
G. Granular photographic. 


U. P. Used as a preservative in developers, and for acidulat- 
ing hypo baths. Lately sodium metabisulphite has been 
introduced to take the place of the potassium salt. 


POTASSIUM NITRATE, KNO; 
Fr. Azotate de Potasse. Ger. Salpetersaures Kali. 


Syn. Nitrate of potash, Nitre, Saltpetre. 


M. W. 101: Sp. G. 2.1062: M. P. 337° C.: B. P. Decomposes 
with deflagration at about 400° C. 


Sol. in water; Ins. in alcohol and ether. 


P. Transparent, colorless or white crystalline powder or 
crystals; cooling, pungent, saline taste. 


Der. Sodium nitrate and potassium chloride in solution are 
evaporated until sodium chloride crystallizes out, then 
decanted and crystallized. GU.S-P. 


U. P. Used in the manufacture of pyroxyline and flash 
powders. Has been recommended as an addition to an 
emulsion to prevent fog. 


POTASSIUM OXALATE, K:C:0.H20 
Fr. Oxalate Neutre de Potasse. Ger. Neutrales Oxalsaures 
Kali, Kaliumoxalat. 

_ Syn. Neutral oxalate of potash. 

M. W. 184: Sp. G. 2.08: M. P. Decomposes when heated. 

Sol. in water; Ins. in alcohol and ether. 

P. Colorless, transparent crystals. 

Der. Obtained by saturating acid oxalate of potash, or 
oxalic acid, with potassium carbonate. 

G. Photographic. 

U. P. Used in the ferrous oxalate developer, and as a 
developer for platinotypes. 


60 MATERIA PHOTOGRAPHICA 


POTASSIUM PERCARBONATE, K.C,0,.H:O 
Fr. Percarbonate de Potasse. Ger. Kaliumpercarbonat. 
M. W. 216. 


Ss. in water. 

P. White, crystalline powder. 

Der. Obtained by electrolysis of potassium carbonate. 
G. Technical. 


U. P. Used as a hypo eliminator, and has been sold under 
many different trade names. 


POTASSIUM PERCHLORATE, KCl1O; 
Fr. Perchlorure de Potassium. Ger. Ueberchlorsaures Kali. 


M. W.. 138.5. 

Ss. in water; Ins. in alcohol. 

P. Colorless powder or rhombic crystals, 
G. ‘Technical. 


U. P. Used in flashlight mixtures. Should be mixed with 
the same precaution as potassium chlorate. 


POTASSIUM PERMANGANATE, KMnO, 


Fr. Permanganate de Potasse. 
Ger. Uebermangansaures Kali. 


Syn. Permanganate of potash. 
M. W. 158: Sp. G. 2.7032: M. P. Decomposes at 240° C. 
Sol. in water, sulphuric and acetic acids and alcohol. 


P. Dark purple crystals having a blue metallic sheen; 
sweetish, astringent taste. 


Der. Obtained by fusing manganese peroxide with potassium 
hydrate or nitrate. 


Le i) Re 


U. P. Used as a reducer for negatives, and when acidulated 
with sulphuric acid reduces the high-lights more than the 
shadows. Used as a neutral solution, it to all intents and 
purposes is an intensifier, as a manganese salt is precipi- 
tated on the silver image rendering it slightly non-actinic 
in color. Is used as the reverser in several screen plate 
color processes. Used as a test for the presence of hypo 
and as a hypo eliminator. In process work, a small 
amount of a 10% solution is used to rid the wet collodion 
silver bath of organic impurities. 


MATERIA PHOTOGRAPHICA 61 


POTASSIUM PERSULPHATE, K:S.0; 


Fr. Persulphate de Potasse. 
Ger. Ueberschwefelsaures Kali. 
Syn. Persulphate of potash, Anthion. 
M. W. 270. M. P. Decomposes below 100° C. 
Sol. in water; Ins. in alcohol. 
P. White crystals. 


Der. By electrolysis of a saturated solution of potassium 
sulphate, 


G. Technical. 


U. P. Used as a hypo eliminator and has been sold under 
various trade names. May also be used as a reducer in 
place of ammonium persulphate and has the advantage 
that it is less likely to contain injurious impurities. 


POTASSIUM AND SODIUM TARTRATE, 
KNaC,H.0.4H.O 


. Sel de Seignette. Ger. Seignettesalz, Rochellesalz, 
Weinsaures Kalinatron. 
Syn. Rochelle or Seignette salts. 


Niet ep. 4s. 1.7/7; M. P..70°-80° C.:-B. P. Loses 
4H-O at 215° C. 


Sol. in water; Ins. in alcohol. 
P. Colorless, transparent crystals or white powder. 


Der. Obtained by boiling together cream of tartar and sodium 
carbonate.- G. U.S.P. 


U. P. Used in printing-out emulsions to form silver tar- 


trate. 
POTASSIUM SULPHIDE, K:S8; 
Fr. Foie de Soufre. Ger. Schwefelkalium, Schwefelleber. 


Syn. Liver of sulphurated potash, Potassium trisulphide. 

M. W. 174: Sp. G. 1.805. 

Sol. in water, alcohol and glycerine; Ins. in ether. 

P. Deliquescent, red, crystalline mass; should be kept well 
stoppered. 

Der. Obtained by fusing sulphur and potassium carbonate. 

G. Technical. 

U. P. Used to precipitate the silver from waste photographic 
solutions, but recently has been almost entirely replaced 
by sodium sulphide for this purpose. 


62 MATERIA PHOTOGRAPHICA 


POTASSIUM SULPHOCYANIDE, KCNS 


Fr. Sulfocyanure de Potassium. Ger, Rhodankalium, 
Schwefelcyankalium. . 


Syn. Potassium thiocyanate, Sulphocyanate, or Rhodanide. 


M. W.-.972 Sp. G: 1.906: MiP. 172.3° Ci Br eco neses 
at U0. 


Sol. in water, alcohol and acetone. 


P. Transparent, deliquescent crystals. Must be kept well 
stoppered. 


Der. By heating potassium cyanide with sulphur. 
G. Pure. 


U. P. Used in the sulphocyanide toning bath. Is a solvent 
for gelatine and therefore has been used in the develop- 
ment of over-exposed carbon prints. 


SILVER ACETATE, Ag(C.H:O2 
Fr. Acétate d’Argent. Ger. Silberacetat. 
M. W. 167. 


Sol. in water; Ins. in alcohol. 
P. Fine white powder or crystals. 


Der. By adding an alkaline acetate to silver nitrate solution 
or by dissolving silver carbonate in glacial acetic acid. 


U. P. Has been recommended for use in printing-out papers, 
but it yields an image of poor quality and its sensitive- 
ness is about one-twentieth of that of silver chloride. 


SILVER AMMONIO-CARBONATE, Ag,CO:4NH:; 


Fr. Ammonio-Carbonate d’Argent. Ger. Kohlensaures 
Silberoxydammoniak. 
M. W. 229. 


Sol. in water and alcohol. 

P. Not found in the solid form. 

Der. Prepared by adding a solution of ammonium car- 
bonate to a solution of silver nitrate. 

U. P. Sometimes used in emulsion making, particularly in 
positive or lantern slide emulsions. 


MATERIA PHOTOGRAPHICA 63 


SILVER AMMONIO-NITRATE, AgNO:2NH:; 


Fr. Ammonio-Nitrate d’Argent. Ger. Salpetersaures 
Silberoxydammoniak. 


Syn. Ammonio-oxide of silver. 
M. W. 204. 
Sol. in water and alcohol. 


P. Colorless needles, but rarely exists in the solid form, 
being formed in the ammonio-nitrate emulsion making 
processes. 


Der. By mixing a solution of ammonia with silver nitrate 
until the precipitate first formed is redissolved. 


U. P. A solution of silver ammonio-nitrate is sometimes 
used for sensitizing plain paper, but its principal use is 
in emulsion making to form silver bromide. Emulsions 
prepared by the ammonio-nitrate process do not have to 
s ripened by aot as ammonia takes the place of 

eat. 


SILVER BROMIDE, AgBr 


Fr. Bromure d’Argent. Ger. Bromsilber. 
Syn. Bromide of silver. 


Mie Weise. op. G. 6.473: M. P. 427° C.: B. P. Decomposes 
at -700°°C. 


Sol. in sodium thiosulphate, potassium bromide and potassium 
cyanide solutions; practically Ins, in water and ammon- 
ium hydroxide. 


P. Yellow amorphous powder. 


Der. Obtained by adding any soluble bromide to silver 
nitrate solution. In photography, it is always prepared 
in the presence of some vehicle which will suspend it in 
the form of an emulsion, and prevent it from forming 
coarse clots. 


U. P. Silver bromide is the basis of the modern gelatino- 
bromide emulsions, and is the most light sensitive silver 
salt. 


64 MATERIA PHOTOGRAPHICA 


SILVER CARBONATE, Ag:CO; 
Fr. Carbonate d’Argent. Ger. Kohlensaures Silberoxyd. 


M. W. 276. 

Sol. in potassium cyanide, ammonia and sodium thiosulphate ; 
Ins. in water and alcohol, 

P. Yellow granular powder. 

Der. By adding an alkaline carbonate to silver nitrate solu- 
tion. 

U. P. Sometimes formed in the preparation of printing-out, 
gaslight and negative emulsions. 


SILVER CHLORIDE, AgCl 
Fr. Chlorure d’Argent. Ger. Chlorsilber. 


Syn. Chloride of silver, Horn silver, Muriate of silver. 

M.. W:.143.4> -SpoGwo Sele Me Pe 45h 

Sol. in sodium thiosulphate and potassium bromide solutions, 
concentrated sulphuric acid and ammonium hydroxide; 
practically Ins. in water. 

P. White granular powder, which darkens on exposure to 
light, finally turning black. 

Der. Obtained by adding a soluble chloride to silver nitrate 
solution. 

U. P. Formed in the preparation of printing-out emulsions 
and positive emulsions. The higher the proportion of 
silver chloride in an emulsion, the shorter the gradation 
scale. 


SILVER CHROMATE, Ag.CrO, 
Fr. Chromate d’Argent. Ger. Silberchromat. 


McAW. wood: 

Sol. in ammonia and sodium thiosulphate; Ins. in water, 
alcohol and ether, 

P. Red amorphous powder. 

Der. Obtained by adding potassium chromate to silver nitrate 
solution. 

U. P. The formation of a small amount of this salt in a 
printing-out emulsion reduces the scale of gradation, 
making a more contrasty paper suitable for weak nega- 
tives. 


MATERIA PHOTOGRAPHICA 65 


SILVER CITRATE, AgC.H;O, 


Fr. Citrate d’Argent. Ger. Silbercitrate, Citronensaures 
Silberoxyd. 

Syn. Citrate of silver. M. W. 297. 

Sol. in ammonia, sodium thiosulphate and _ potassium 
cyanide; Ins. in water, alcohol and ether. 

P. Curdy white powder. 

Der. Obtained by adding an alkaline citrate to silver nitrate 
solution. 

U. P. When formed in small proportions in printing-out 
emulsions, has a definite influence on the keeping quality 
of the paper—seemingly it has a preservative effect. 
Formed in silver chloride gaslight emulsions, it tends to 
increase contrast and reduce fog. 


SILVER CYANIDE, AgCN 
Fr. Cyanure d’Argent. Ger. Silbercyanid. 


M. W. 134: Sp. G. 3.95: M. P. Decomposes when heated. 


Sol. in ammonia, potassium cyanide and sodium thiosulphate 
solutions; Ins. in water, alcohol and ether. 


P. White powder which darkens on exposure to light; very 
poisonous. 


Der. Obtained by adding an alkaline cyanide to a solution 
of silver nitrate. 


U. P. Formed in the preparation of the blackening solution 
in Monckhoven’s intensifier. 


SILVER IODIDE, Agl 
Fr. Iodure d’Argent. Ger. Iodsilber. 
Bie op. G, 5.6/5: M. P. 556° C. 


Sol. in potassium cyanide and sodium thiosulphate solutions. 
Ins. in water, ammonia, alcohol and ether. 
P. Pale yellow powder, darkening on exposure to light. 


Der. Obtained by adding a soluble iodide to silver nitrate 
solution. 


U. P. Silver Iodide is sometimes formed in small propor- 
tions in gelatino-bromide emulsions, tending to restrain 
fog during digestion and produces greater sensitiveness 
(see Potassium Iodide). Silver Iodide is also employed 
in the wet plate process. The negative silver bath for 
sensitizing wet collodion plates should be saturated with 

silver iodide before using. 


66 MATERIA PHOTOGRAPHICA 


SILVER NITRATE, AgNO; 


Fr. Azotate d’Argent. re Silbernitrat, Salpetersaures 
ilber. 


M. W. 170: Sp. G. 4.352: M. P. 218° C.: B. P. Decomposes. 
Sol. in water, ether and glycerine; Ss. in alcohol. 


P. Colorless, rhombic plates. Is not in itself sensitive to 
light, but is very easily reduced to the metallic state in 
the presence of organic materials: as the skin, paper or 
gelatine. 


Der. Silver is dissolved in dilute nitric acid, the solution 
evaporated. 


G. Pure crystals, photographic. 


U. P. Silver Nitrate is the salt from which are made all 
the sensitive materials of photography in which silver is 
used. In process work, is occasionally used in the ae 
bath for steel plates. 


SILVER PHOSPHATE, Ag;POs 
Fr. Phosphate d’Argent. Ger. Silberphosphat. 


Syn. Normal silver orthophosphat. 
M. W.. 419: Sp:-G. 7.320: Me Po 


Sol. in ammonia, potassium cyanide and sodium thiosulphate 
solutions, and organic acids; Ins, in water, alcohol and 
ether. 


P. Heavy yellow powder; turns brown when heated, or on 
exposure to light. 


Der. Obtained by adding phosphoric acid to silver nitrate 
solution. 


U. P. When formed in small proportions in printing-out 
emulsions, gives a long scale of gradation suitable for soft 
prints from hard negatives; acts very similarly when 
formed in silver chloride gaslight emulsions. 


MATERIA PHOTOGRAPHICA 67 


SILVER SULPHIDE, Ag:S 
Fr. Sulfure d’Argent. Ger. Silbersulfid. 
M. W. 248: Sp. G. 6.85-7.32: M. P. 842° C.: B. P. Decom- 


poses. 


Sol. in concentrated sulphuric and nitric acids; Ins. in water 
and alcohol. 


P. A brownish-black powder. 


Der. Obtained by mixing an alkaline sulphide with silver 
nitrate solution. Also formed when liver of sulphur is 
added to old hypo baths. 


U. P. Silver sulphide is the salt formed when gaslight or 
bromide prints are sepia toned in the sulphide bath. 


SODIUM ACETATE, NaC,H;0.3H2O 
Fr. Acétate de Soude. Ger. Essigsaures Natron. 


Syn. Acetate of soda. 

Bee tao 9p. cx. LA: M. P. 58° C. 

Sol. in water; Ss. in alcohol. 

P. Colorless, transparent, efflorescent crystals. 


Der. Prepared by neutralizing acetic acid with sodium car- 
bonate. 


G. U.S.P. Granulated. 


U. P. Used in the gold toning bath. Double fused sodium 
acetate is sometimes used, having a slight alkaline 
reaction, makes the toning bath work more quickly. It is 
also more free of organic impurities. 


68 MATERIA PHOTOGRAPHICA 


SODIUM BICHROMATE, Na:Cr.0,2H:O 


Fr. Bichromate de Soude. Ger. Doppelt Chromsaures 
Natron. 


Syn. Dichromate of soda, Acid sodium chromate. 


M. W. 298: Sp. G: 2.52: M. RB. Losés 2he@aapenn ee 
B. P. Decomposes. 


Sol. in water; Ins. in alcohol. 
P. Red, deliquescent, crystalline fragments. 


Der. Obtained in similar manner to potassium salt. (QV.) 
G. Technical. 


U. P. Used in the same manner and for the same purposes 
as the potassium salt. One part of potassium bichromate 
is equivalent to 1.10 parts of sodium bichromate. In proc- 
ess work, is sometimes used to replace the ammonium 
and potassium salts for sensitizing, but its deliquescent 
nature is a disadvantage. 


SODIUM BISULPHITE, NaHSO: 


Fr, Bisulfite de Soude. Ger. Saures Schwefeligsaures 
Natron, Natrium Bisulfit. 


Syn. Acid sulphite of soda. 

M. W. 104: Sp. G. 1.48: M. P. Decomposes. 

Sol. in water; Ins. in alcohol. 

P. White crystalline powder; faint sulphurous odor. 


Der. Prepared by passing sulphurous acid gas through car- 
bonate of soda solution. 


G. U.S.P. or special photographic. 


U. P. Used for acidulating and preserving fixing baths 
supplying both the sulphite and acid necessary. For 
preparing neutral sulphite solution which is cee 
used as a preservative for pyro developer. Can be sub- 
stituted weight for weight for potassium metabisulphite. 
For photographic purposes, sodium bisulphite should be 
free from iron. 


MATERIA PHOTOGRAPHICA 69 


SODIUM BORATE, Na.B.0,10H.O 
Fr. Borate de Soude. Ger. Borax, Borsaures Natron. 


Syn. Borax, Sodium tetraborate, Pyroborate, Biborate. 
M. W. 382: M. P. Red-heat. 

Sol. in water and glycerine; Ins, in alcohol. 

P. White crystals or powder. 


Der. Obtained from the native borax, or by neutralization of 
native boric acid. 


eer Uo. 


U. P. Used in gold toning baths, and as an accelerator with 
hydroquinone and eikonogen developers. Can be used as 
a restrainer with the metol-hydroquinone developer for 
gaslight papers, and produces a print having a warm 
brownish-black. 


SODIUM CARBONATE, 
Na:CO;10H:O (cryst): Na.Cos (dry) 


Fr. Carbonate de Soude. Ger. Soda, Kohlensaures Natron, 
Natriumcarbonat. 


Syn. Soda, Washing soda, Carbonate of soda. 


Mower coo. op. G. 1446; M. P. Loses 5H:0 at 12.5° C., and 
mee at oF. C.: B. P, 106°C. 


Sol. in water and glycerine; Ins. in alcohol. 


P. Colorless crystals or white powder; strong alkaline taste; 
effloresces in alr. 


Der. Obtained by converting salt into sodium sulphate, and 
then decomposing the latter by roasting with limestone 
and coal. 


Sag ech ge 


U. P. Sodium carbonate is the principal alkali used for 
developers; in addition to the crystal form there is a 
grade known as “dry powder” which is extensively used 
For all practical work, 37 parts of the dry powder are 
equivalent to 100 of the crystals. 


70 MATERIA PHOTOGRAPHICA 


SODIUM CHLORIDE, NaCl 


Fr. Chlorure de Soude, Selmarin. Ger. Chlornatrium, 
Sal Gemmae. 
Syn. Muriate or chloride of soda, Salt, Common table-salt. 
M. W. 58.5: Sp. G. 2:16): M. P) 804 Pee 


Sol. in water; practically Ins. in alcohol; Ins. in concentrated 
hydrochloric acid. 


P. Colorless, transparent crystals or white, crystalline 
powder. 


Der. Obtained native or by purification from sea water. 
ks. J OLS 


U. P. Used in the preparation of chloride emulsions. Also 
acts as a restrainer, but is weaker than the alkaline 
bromides. 


SODIUM CITRATE, 2Na;C.H;O;7.11H2O 
Fr. Citrate de Soude. Ger. Citronensaures Natron. 


Syn. Citrate of soda, Neutral citrate of soda. 


M. W. 714: M. P. Loses 11H.O at 150° C.: B. P. Decom- 
poses. 


Sol. in water; Ss. in alcohol. 


P. White crystals or granular powder; pleasant acid taste; 
very deliquescent. 


Der. Obtained by neutralizing citric acid with sodium car- 
bonate. 


Cry 


U. P. Used as a preservative in albumen papers, also to 
form silver citrate in printing-out emulsions. Is also 
used as a restrainer in development. 


MATERIA PHOTOGRAPHICA 71 


SODIUM HYDRATE (Caustic), NaOH 
Fr. Soude Caustique. Ger. Aetznatron. 
Syn. Caustic soda, Sodium hydroxide. 
Pew. a0. Sp. G. 2.13: M. P. 318° C.: B. P, White heat. 
Sol. in water, alcohol and glycerine. 


P. White, deliquescent pieces, lumps or sticks; crystalline 
fracture. Keep well stoppered, absorbs water and carbon 


dioxide from the air. Should not be handled with the 
fingers. 


Der. Obtained by decomposing sodium carbonate with lime. 


USP. 


U. P. Used as an accelerator in development. Most gen- 


erally used with low energy developers, as hydroquinon, 
etc: 


SODIUM NITRATE, NaNO; 
Fr. Azotate de Soude. Ger. Salpetersaures Natron. 
Syn. Cubic, Chili, or Soda nitre or Saltpetre. 
Meo sp G. 220/: M. P. 316° C.: B, P. Decomposes. 
Sol. in water and glycerine; Ss. in alcohol. 
P. Colorless, transparent crystals. 
Der. Found native. 
G. U-S-P. 


U. P. Not often used in photography, although it is credited 


with imparting a brownish-black tone to developed silver 
images. 


SODIUM NITRITE, NaNO, 

Fr. Azotite de Soude. Ger. Salpetrigsaures Natron. 
Syn. Nitrite of soda. 
oe eooe op. G. 2.157) M. P. 213° C.: B. P. Decomposes. 
Sol. in water; Ss. in alcohol and ether. 
P. Slightly yellowish or white crystals. 
Der. Prepared by fusing the nitrate or neutralizing nitrous 

acid. 
ARTS 


U. P. Used in the diazotype process and in the preparation of 
photometer paper. 


72 MATERIA PHOTOGRAPHICA 


SODIUM NITROPRUSSIDE 
NasFe(CN)s(NO)2H:0 | 
Fr. Nitroprussiate de Soude. Ger. Nitroprussidnatrium. 
Syn. Sodium nitroprussiate. 


M. W. 298: Sp. G. 1.6803. 
Sol. in water and alcohol. 
P. Ruby-red, transparent crystals. 


Der. Sodium ferrocyanide solution is treated with nitric 
acid. 


G. Pure. 


U. P. Is one of the most light sensitive iron salts, and is 
sometimes used in iron printing processes. 


SODIUM OXALATE, Na:C.0, 
Fr. Oxalate de Soude. Ger. Oxalsaures Natron. 


Syn. Oxalate of soda. 

M. W. 134. 

' Sol. in water; Ins. in alcohol. 

P. White, crystalline powder; poisonous. 


Der. By neutralizing an oxalic acid solution with sodium 
carbonate. 


G. Pure. 


U. P. Not often used because of its low solubility; is, how- 
ever, sometimes used in the platinotype process. 


SODIUM PHOSPHATE, Na:HPO,12H2O0 
Fr. Phosphate de Soude. Ger. Phosphorsaures Natron. 


Syn. Disodium phosphate, Disodium orth-phosphate. 

M. W. 358: Sp..G. 1.5235: M. P. 35° Co: BY Piosestieee? 
ate 00sec. 

Sol. in water; Ins. in alcohol. 

P. Colorless, transparent crystals. 

Der. By treating calcium phosphate with carbonate of soda. 

(SU See. 

U. P. Used in gold toning baths and sometimes in connec- 
tion with silver chloride emulsions. 


MATERIA PHOTOGRAPHICA 73 


SODIUM SILICATE, Na:SiO; 


Fr. Silicate de Soude. Ger. Natronwasserglas. 
Syn. Soluble glass, Soda water-glass. 
Bee i242 M. P._1018° C. 
Sol. in water and alkalis; Ins. in alcohol and acids. 


P. White to gray-white lumps or powder. Also obtainable 
in a commercial form as a syrupy yellowish liquid. 


Der. Silica, calcined soda and coal are heated together in a 
crucible, the mass when cold, is extracted with water, 
followed by evaporation of the water. 


G. Usually bought in the grade known as “Technical solu- 
tion.” 


U. P. Used principally in process work, either alone or with 
albumen to form a substratum for coating collotype print- 
ing plates. 


SODIUM SULPHANTIMONIATE, Na;SbS8.9H:O 


Fr. Sulfoantimoniate de Soude, Sel de Schlippe. 
Ger. Schlippesche Salz. 

Syn. Schlippe’s salt, Sodium thioantimonate. 

M. W. 479. 

Sol. in water. 

P. Colorless or yellow crystals. 

Der. Obtained by boiling sulphide of antimony, milk of lime 
and sodium carbonate. 

G. Pure. 

U. P. Used for blackening negatives after bleaching with 
mercuric chloride, and sometimes used for toning bromide 
prints. 


SODIUM SULPHATE, Na.S0O.10H:O 


Fr. Sulfate de Soude. Ger. Schwefelsaures Natron. 
Syn. Glauber’s salt. 
Mi Ws Sen. 
Sol. in water; Ins. in alcohol. 
P. Colorless, efflorescent crystals. 
Der. Is yielded as a by-product in the salt cake process. 
G. Technical. 


U. P. Finds considerable use in the preparation of barium 
sulphate for surface coating photographic raw paper 
stock. 


74 MATERIA PHOTOGRAPHICA 


SODIUM SULPHIDE, Na.S9H.O 
Fr, Sulfure de Soude. Ger. Natrimsulfid. 


Syn. Sulphide of soda. 

M. W. 240: Sp. G. 1.856. © 

Sol. in water; Ss. in alcohol; Ins. in ether. 

P. Yellow or brick-red lumps. Deliquescent, must be kept 
well stoppered. 

Der. Prepared by fusing sodium carbonate with sulphur. 

G. Technical. 

U. P. Used for the sulphide toning of bromide and gaslight 
prints. Sodium sulphide should not be kept near sensitive 
materials as it is likely to fog them and bring about 
deterioration. In process work, a three to five per cent. 
solution is used as the blackening agent in the intensifica- 
tion of wet collodion negatives; for this purpose it is 
better than ammonium sulphide. 


SODIUM SULPHITE, 
Na2SOs;7H.2O(cryst) NazSos(dry) 
Fr. Sulfite de Soude. Ger. Natriumsulfid. 


Syn. Sulphite of soda. 


M. W.:.252: Sp. GG. 1:5939: Mo Poses 7H.0 atclo0. 32 
B. Po Decompases. 


Sol. in water; Ins. in alcohol. 


P. White crystals or powder. The crystals are efflorescent, 
becoming readily oxidized to sulphate. 


Der. Prepared by passing sulphurous acid gas over moistened 
sodium carbonate. 


G. U.S.P. Crystals or Dry Powder. 


U. P. Sodium sulphite is a vigorous absorbent of oxygen, 

therefore it is used as a preservative of developing agents. 

It is one of the constituents of the acid fixing bath. The 

_. dry powder form, which is now almost universally used in 

- photography, is twice as strong in sulphite as the 
crystalline. . 


MATERIA PHOTOGRAPHICA 75 


SODIUM THIOSULPHATE, Na:.S:.0;5H:.O 


Fr. Hyposulfite de Soude. Ger, Fixirnatron, 
Unterschwefligsaures Natron. 
Syn. Sodium hyposulphite. 
M. W. 248: Sp. G. 1.729: M. P. 48° C.: B. P. Decomposes. 
Sol. in water and oil of turpentine; Ins. in alcohol. 
P. White, transparent crystals. 


Der. The crude sulphide liquors resulting from the Le 
Blanc soda process are exposed to air and oxidized, 
yielding calcium thiosulphate. This solution is boiled with 
sodium sulphate and subsequently crystallized. 


G. Technical. 


U. P. Its principal use is in the preparation of fixing baths 
for films, plates and papers. It is one of the ingredients 
of Farmer’s ferricyanide-hypo reducer. 


SODIUM VANADATE, Na:VOs,. 
Fr. Vanadate de Soude. Ger. Natriumvanadat. 


Syn. Sodium orthovanadat. 

M. W. 184: M. P. 866° C. 

Sol. in water; Ins. in alcohol. 

P. White, crystalline powder. 

Der. By solution of ammonium vanadate in sodium 
hydroxide solution and crystallization. 


U. P. Sometimes used to increase the contrast of printing- 
out emulsions. 


STARCH, C;HwOs 
Fr. Amidon. Ger. Starke. 


Sp. G. 1.499-1.513: M. P. Does not melt: B. P. Decomposes 
and chars. 

Ins. in cold water, alcohol and ether. Makes a jelly with 
hot water. 

P. White, amorphous powder. Starch when heated to about 
204° C. is converted into dextrine. 

Der. From corn, maze, rice, potatoes, arrow root, etc. 

U. P. Used in the preparation of photographic mountants, 
and also for sizing photographic paper. Is sometimes 
used as a matting agent, being added to emulsions to dull 
the surface. 


76 MATERIA PHOTOGRAPHICA 


STRONTIUM BROMIDE, SrBr.6H:O 
Fr. Bromure de Strontium. Ger. Strontiumbromid. 
Syn. Bromide of strontia. 
M. W. 355.5. 
Sol. in water; Ss. in alcohol, 
P. Colorless crystals. 


Der. Prepared by neutralizing hydrobromic acid with stron- 
tium hydrate. 


Gy eULRStP: 
U. P. Sometimes used in collodion emulsions to increase 


contrast. The anhydrous salt, SrBr2, is sometimes used 
and occurs as a white deliquescent powder. 


oe 


STRONTIUM CHLORIDE, 
SrCl.6H,O(crystals) SrCl.(dry) 
Fr. Chlorure de Strontium. Ger. Strontiumchlorid. 
Syn. Chloride of strontia. 
M. W. 266.5: Sp. G. 1.964: M. P. Loses 6H.2O at 112° C. 
Sol. in water and alcohol. 
P. White needles. 


Der. Calcium chloride is fused with sodium carbonate, the 
yield extracted with water, concentrated and crystallized. 
GC US. 


U. P. Used in the preparation of chloride emulsions, yielding 
more contrast and a shorter scale. The anhydrous salt, 
SrCl:, occurring as a white powder is sometimes used. 


STRONTIUM IODIDE, SrI.6H.O 

Fr. Iodure de Strontium. Ger. Strontiumiodid., 
Syn. Iodide of strontia. 
M. W. 449: Sp. G. 4.415. 
Sol. in water, alcohol and ether. 
P. Yellowish, granular powder. 
Der. By treating strontium carbonate with hydriodic acid. 
G. U.S.P. Fused. 
U. P. Uses, the same as for strontium bromide. (QV.) 


MATERIA PHOTOGRAPHICA 77 


THIOCARBAMIDE, CS(NH:). 
Fr. Sulfo-urée, Sulfocarbamide. Ger. Thiocarbamid, 
Sulfoharnstoff. 
Syn. Sulphourea, Thiourea. 


M. W. 76: Sp. G. 1.406: M. P. 180° C.: B. P. Sublimes in 
vacuo at 150°-160° C. 


Sol. in cold water, ammonium sulphocyanide solution and 
ether; Ins, in cold alcohol. 


P. White, lustrous crystals. 


Der. Obtained by heating ammonium sulphocyanide for sev- 
eral hours at a temperature of 161° C. 


U. P. Used in the gold toning bath and has been suggested 
as an addition to eikonogen developer to produce reversal. 
Thiocarbamide can also be used for clearing yellow stains 
from prints and plates. 


THIOSINAMINE, CS(NH:)NHC;H; 
Fr. Sulfophenylurée. Ger. Thiosinamin Allylsulfoharnstoff. 
Syn. Allyl sulphocarbamide, Allyl sulphourea. 
M. W. 116. 
Sol. in alcohol and ether; Ss. in water. 
P. Colorless crystals; garlic odor. 


Der. Prepared by the action of ammonia and alcohol on 
allyl sulphocyanate (oil of mustard). 


U. P. Has been tried as a fixing agent, but is not nearly as 
energetic as hypo. 


TIN (Stannous) CHLORIDE, SnCl.2H20 
Fr. Chlorure d’Etain. Ger. Stannochlorid. 


Syn. Tin protochloride or dichloride, Tin salt. 

hee yee on. G, 2./):.M. P.37.7° C.:-B. PB. Decomposes: 
Sol. in water and alcohol. 

P. White crystals. 

Der. Prepared by the action of hydrochloric acid on tin. 

G. Technical crystals. 


U. P. Can be used as a blackening agent after bleaching with 
mercuric chloride. 


78 MATERIA PHOTOGRAPHICA 


URANIUM CHLORIDE, UO.CI1.H:O 
Fr. Chlorure d’Urane. Ger. Uranylchlorid. 


Syn. Uranyl chloride or oxychloride. 

M. W. 361. Sol. in water and alcohol. 

P. Deliquescent, greenish-yellow flakes; poisonous. 

Der. GS by dissolving uranic oxide in hydrochloric 
acid. 

U. P. Sometimes used as a sensitive salt for printing-out 
paper, and added to a chloride emulsion increases con- 
trast. 


URANIUM NITRATE, UO.(NOs3):6H:O 
Fr. Azotate d’Urane. Ger. Uranylsalpetersaure. 


Syn. Uranyl nitrate, Uranium oxynitrate. 
M. W. 504:-Sp. G. 2.807: M;-P. 602° Cos Bier 
Sol in water, alcohol and ether. Poisonous. 


P. Yellow, rhombic crystals; efflorescent, greenish color by 
reflected light. 


Der. Prepared by dissolving uranic oxide in nitric acid. 
Go s-U-S:Pi 


U. P. Used in printing-out emulsions and with potassium 
ferricyanide in the toning of bromide prints and intensi- 
fication of negatives. Used in conjunction with silver 
nitrate in the preparation of uranium silver papers for 
gaslight printing. Also used in the uranium mercuro- 
uranotype and the platino-uranotype processes. 


VANADIUM CHLORIDE, 2V0.4HCI13H:.O 
Fr. Chloure de Vanade. Ger. Chlorvandium. 


Syn. Hypovanadic-hydrochloride, Divanadyl-tetrachloride. 
M. Wt 306: Sp. tae Sol. in water and alcohol. 
P. Dark green syrupy mass; poisonous. 


Der. Prepared by dissolving vanadic anhydride in hydro- 
chloric acid. 


U. P. Used for imparting a green tone to bromide prints, 
and is one of the ingredients of the Donisthorpe dye 
printing process. Lumiére, in 1894, introduced a van- 
adium printing paper in which a gelatinized paper was 
sensitized with a mixture of vanadium chloride in alcohol 
and water, printed under a positive transparency and 
subsequently treated with paramidophenol. 


MATERIA PHOTOGRAPHICA 79 


ZINC BROMIDE, ZnMr. 
Fr. Bromure de Zinc. Ger. Zinkbromid. 


heey orezzo op. G. 4219: M. P. 394° C.: B. P. 650° C. 
Sol. in water, alcohol and ether. 
P White, hygroscopic, crystalline powder. 


Der. Prepared by dissolving zinc carbonate in hydrobromic 
acid. 


Goro. 


U. P. Used in the preparation of collodion emulsions. 


ZINC CHLORIDE, ZnCl. 
Fr. Chlorure de Zinc. Ger. Zinkchlorid. 


Mew is0- Sp. G. 291: M. P. 262° C:.: B. P 730° C. 
Sol. in water, alcohol and ether. 


P. White, granular, deliquescent crystals; poisonous. Keep 
well stoppered. 


Der. By the action of hydrochloric acid on zinc, with sub- 
sequent crystallization. 


53: 


U. P. Used in the preparation of collodion emulsions. 


ZINC IODIDE, ZnI, 
Fr. Iodure de Zinc. Ger. Zinkiodid. 

Mow. 319: Sp. G. 4.696: M. P. 446° C.: B. P. 624° C. 
Sol. in water, alcohol and ether. 

P. White, deliquescent powder. Keep well stoppered. 
Der. Prepared by dissolving zinc oxide in iodic acid. 
Se De oe 

U. P. Used in the preparation of collodion emulsions. 


80 MATERIA PHOTOGRAPHICA 


DEVELOPERS 


There are upwards of three hundred (300) known 
photographic developing agents, most of them are, how- 
ever, of purely laboratory interest. Some have become 
obsolete and many are no longer manufactured, therefore, 
only the developing agents in current use will be described 
in this section: 


Developers obtained from Monohydric Phenols: 


sou 

PARAMIDOPHENOL, CoHs (1: 4) 

NH; 

Obtained by reducing para-nitrophenol with tin and 

hydrochloric acid. Occurs in colorless crystals with an 

M. P. of 184° C., also forms a crystalline hydrochloride. 

“Rodinal,” the concentrated liquid developer, contains 

para-amidophenol-hydrochloride. There is a solid form 
known as Unal. 


MONO-METHYL-PARAMIDO-PHENOL, 
C.H.(OH) (NHCHs) 1:4 


Obtained by methylating paramidophenol, and more 
recently by the direct synthesis of methylamine and 
hydroquinone. 


Elon or “Metol” is the sulphate and is also known as 
Rhodol, Adne, Satrapol, Genol, etc. Elon or Metol in 
conjunction with hydroquinone is one of the best known 
developers. It also works well in conjunction with pyro. 


DI-AMIDO-PHENOL, CsH;s(OH)(NH:)(NH:2)1:2:4 


Obtained by reducing 1:2:4 dinitrophenol with tin and 
hydrochloric acid, forms salts with sulphuric and hydro- 
chloric acids. 


“Amidol” can be either the sulphate or chloride, and is 
one of the best developers for bromide and gaslight 


MATERIA PHOTOGRAPHICA 81 


papers. It does not keep very well in solution. Recently, 
methods of prolonging the life of Amidol solutions have 
been suggested by the addition of a small amount of lactic 
acid or a small proportion of metol. Amidol and Acetone 
sulphite form a powerful developer. 


PARA-AMIDO-SALIGENIN, 
CoH3(CH:0H)(OH)(NH:2)1: 2:3 


Occurs as an easily soluble white powder, somewhat 
similar in properties to Amidol, with the advantage of 
allowing the preparation of very concentrated solutions. 
“Eidinol,’ made by Bayer, is the trade name of this 
material. It combines well with hydroquinone and acetone 
sulphite. 


/ONa(1) 
ee ENE, CHG (4) 


| 
CesHs.NHs 


The sodium salt can be used in a manner similar to 
Rodinol. Is sold as “Diphenal.” 


PARA-OXY-PHENYL-GLYCOCOLL, 
CsH.:(OH) (NH.CH2.CO:H)1: 4 


Obtained by heating paramidophenol with monochloracetic 
acid in aqueous solution. ‘‘Glycin” is the trade name for 
this preparation. It gives a very pure black image and 
solutions keep well. Used principally for stand develop- 
ment, owing to the fact that it does not produce chemical 
fog with prolonged development. 


METHYL-ORTHO-AMIDO-PHENOL, 
C.H.(OH) (NHCH;)1 2 


One molecule of hydroquinone with two molecules of 
methylorthoamidophenol forms the basis of “Ortol.” 


82 MATERIA PHOTOGRAPHICA 


The following two naphthalene compounds are used as 
developers: 


SODIUM AMIDO-BETA-NAPHTHOL-MONO- 
SULPHONIC ACID, Ci.H;(OH) (NH:2)(SO;Na) 


Occurs in tabular crystals, white or slightly violet tinted. 
Is frequently sold blended with potassium metabisulphite. 
Is known commercially as ‘“Fikonogen.” Eikonogen is a 
useful developer for plates which have received short 
exposure, and works very well in conjunction with 
hydroquinone. 


SODIUM AMIDO-NAPHTHOL-DI-SULPHONATE, 
CyHi(N H2) (OH) (SO;Na)2 


A yellowish powder, frequently combined with meta- 
bisulphite as a preservative. This body forms the basis 
of the developer “Diogen.’ Diogen gives negatives of 
a good pure black color having good gradation; not very 
susceptible to bromide. 


Developers obtained from Dihydric Phenols: 
PARA-DI-OXY-BENZINE, C;H:(OH):l: 4 


The best preparation occurs as almost white crystals or 
needles obtained by _ recrystallizing the commercial 
product in the presence of SOx Is known commercially 
as “Hydroquinone.” Hydroquinone alone gives strong, 
hard negatives of a bluish-black tone and is quite opposed 
to Metol in performance, as with Hydroquinone the 
shadow detail does not come up until the high lights have 
acquired considerable density; in other words, it produces 
density rather than detail, which makes it of value in 
combination with the softer working Metol. Can be 
successfully used with Edinol and Fikonogen. 


MONOCHLOR and MONO-BROM-HYDRO- 
QUINONE, Ce.H:C1(OH)>. and C.HsBr(OH). 


The Monochlor is prepared by leading Chlorine gas 
through Hydroquinone dissolved in benzol, while the 
Monobrom is obtained by adding a solution of bromine in 
benzol to a Hydroquinone benzol solution, subsequently 
evaporating the benzol and crystallizing from ligrion. 
Commercially these bodies are known as “Adurol,” the 
monobrom being the product of Schering, and the mono- 


MATERIA PHOTOGRAPHICA 83 


chlor, the product of Hauff. Adurol in performance comes 
between Hydroquinone and the rapid types of developers, 
such as Metol and Rodinal. Solutions are not readily 
oxidized and may be repeatedly used. 


PYROCATECHOL, C.H:(OH)21: 2 


Occurs as a white crystalline powder, something like 
Hydroquinone in appearance. Is soluble in alcohol, ether 
and water. Does not keep well in solution. If a 5% solu- 
tion of borax be used as restrainer, very good brown-black 
tones may be obtained by direct development on gaslight 
and bromide paper. It is also sold under the name of 
“Kachin.” 


RESORCIN, C.H:i(OH).1: 3 


Is in itself of no use as a developer, but two Amido 
derivatives from excellent developers. “Diamido Resorcin,” 
CesH2(NH:2)2(OH)2 and “Triamido Resorcin.” Diamido 
Resorcin Hydrochloride is sold as “Dianine,” is a fawn 
colored powder working similarly to Amidol, needing only 
soda sulphite to produce an energetic developer. ‘Triamido 
Resorcin Hydrochloride is sold as ‘“Reducin.” 


Developers obtained from Trihydric Phenols: 
PYROGALLOL, C.H;:(OH)s1: 2:3 


Familiarly known as “Pyrogallic Acid” or “Pyro,” a fine, 
very light, white powder which oxidizes very quickly in 
solution. Produces negatives of a yellowish color unless 
sodium sulphite is used. It also stains the fingers. Used 
in conjunction with Metol and Hydroquinone forms an 
excellent tank developer, and with Metol an excellent 
developer for portrait negatives. The accelerators used 
with Pyro can be Ammonia, Sodium Carbonate, Potassium 
Carbonate or Acetone. 


PINAKOL P 


Is a good developer made by substituting in the Pyro 
potash developer the alkali by half the equivalent amount 
of sodium amidoacetate. This developer works more 
rapidly than ordinary pyro, gives clearer negatives and 
does not stain the fingers. 


84 MATERIA PHOTOGRAPHICA 


DYES 


Of the several hundred known dyes for color sensitiz- 
ing, desensitizing safe lights, mordanting processes, and 
the preparation of light filters, but comparatively few are 
really useful and practical in performance. Only those 
which have found continued and successful application 
in photographic processes will be dealt with: 


SENSITIZING DYES 
For Orthochromatic Emulsions: 


ERYTHROSIN is most generally used for ortho- 
chromatizing silver bromide emulsions. It sensitizes for 
yellow and green. 


EOSIN is also used for orthochromatizing but does 
not give as great a sensitiveness as Erythrosin, and is more 
likely to produce fog in the emulsion. 


The usual practice when orthochromatizing emulsions 
with either of these two dyes is to add them to the emul- 
sion during the course of manufacture instead of bathing. 


MONO-BROM-FLUORESCEIN is also used as a 
yellow-green sensitizer for silver bromide. 


In the preparation of the so-called self-screened emul- 
sions a yellow dye is incorporated with the emulsion and 
acts as though a yellow filter were employed upon the 
lens, usually this result is obtained by adding to the emul- 
sion a small amount of Filter Yellow K. 


With both Erythrosin and Eosin the sensitizing effect 


is greatly increased by using them in conjunction with 
ammonia. 


For Panchromatizing Emulsions: 


For Panchromatizing it is usual to employ two or 
more dyes to secure the desired result. 


MATERIA PHOTOGRAPHICA 85 


CYANINES 


CYANIN, a blue dye, is very useful as a sensitizer 
for silver bromide where a panchromatic effect is desired. 
It confers a sensitiveness to yellow, orange and red rays 
with a minimum of sensitiveness between E and F. Its 
chief disadvantage is a tendency to produce fog, and it 
has been almost entirely replaced by the Isocyanines. 


DICYANIN sensitizes silver bromide emulsions as 
far as the red line A, with minimum sensitiveness between 
E and F. The prepared plates, however, do not keep very 
well. 


ISOCYANINES 


ETHYL RED, which occurs as green crystals, soluble 
in water and alcohol, sensitizes bromide emulsions with 
fair uniformity from violet to red with a small minimum in 
the green. It does not, however, sensitize very far into 
the red end. 


ORTHOCHROME—T is an excellent sensitizer for 
green, yellow, orange and red, diminishing the general 
sensitiveness but very little, and has no tendency to fog 
the emulsion. 


PINACYANOL. This is one of a new class of dyes 
which gives great sensitiveness to yellow, orange and 
red. Is particularly useful in the preparation of plates for 
three-color photography, for recording the blue sensation. 
Pinacyanol does not sensitize for green and so the plates 
may be developed in dark green light (F line) without 
danger of fog. Pinacyanol may be added to an emulsion 
during the process of manufacture, or may be used to 
bathe the finished plates or films. 


PINACHROM sensitizes bromide emulsions up to 
the line B, producing plates which render dark red 
extremely well; does not tend to produce emulsion fog 
and the finished plates will keep for a long time. This dye 
can either be added to the emulsion or the finished plates 
may be bathed. 


86 MATERIA PHOTOGRAPHICA 


PINACHROM VIOLET has one great advantage 
over Pinacyanol: in that it combines with the green sen- 
sitizers with less danger of fog and influence on the keep- 
ing quality of the finished plates. Pinachrom Violet sen- 
sitizes almost to line B. Can be added to the emulsion 
or used for bathing the finished plates. 


PINAVERDOL is excellent for conferring green 
sensitiveness, and may be added to the emulsion or used 
for bathing the finished plate. 


PINAFLAVOL is the newest sensitizer for green and 
combines much better with Pinacyanol than does Pinaver- 
dol. Can be added to the emulsions or used for bathing 
the finished plates. Confers no red sensitiveness. 


In Panchromatizing it is always found that there are 
definite maxima and minima of sensitiveness and recently 
the addition of Auramine has been suggested to the pan- 
chromatizing dyes as a means of securing a more uniform 
panchromatic effect. It is only necessary to use a very 
small amount of this dye. 


KRYPTOCYANINE sensitizes very strongly for red 
and has only recently been introduced. It gives a 
maximum sensitiveness at wave length 770; confers no 
green sensitiveness. Other sensitizers of this class for the 
deep red which have recently been introduced, are: 
Beta-naphtha-cyanole, which sensitizes with a strong maxi- 
mum in the deep red at wave length 690, and also sen- 
sitizes for green but less so than Pinacyanol. Acetamino- 
cyanole, when added to an emulsion yields a maximum 
sensitiveness at wave length 730, can also be used for 
bathing the finished plates. 


During the war Pinacyanol and Pinaverdol were 
synthesized in this country at the Color Laboratory at 
the Bureau of Chemistry at Washington, and were also 
prepared in England by Prof. Pope, under the names of 
Sensitol Red and Sensitol Green; both the English and 
American dyes were in every way equal to the German 
product. 


MATERIA PHOTOGRAPHICA 87 


DESENSITIZING DYES 


Recently Ltuppo-Cramer discovered the desensitizing 
action of the Azo dye known as Phenosafranine, and also 
of other dyes of the same class on ordinary and pan- 
chromatic plates. A further application of the use of 
Phenosafranine is the use of the substance in very small 
amounts for development under ruby or orange light of 
great brilliancy, so that even a very sensitive plate or even 
orthochromatic plates may be developed under the direct 
rays of the dark-room light. It has been found that 10 cc. 
of a 100,000 solution of Phenosafranine added to 100 cc. 
of any desired developer permits of the safe development 
without risk of fog, even in a very bright ruby light. In 
addition to Phenosafranine the following dyes of the 
Safranine class possess valuable desensitizing properties: 


Di-methyl-pheno-safranine. 

Tetra-methyl-safranine. 

Tolu-safranine (ordinary safranine). 
Methyl-tolu-safranine (Safranine MN). 
Dimethyl-benzoxylyl-safranine (Giroflé). 
Tetra-ethyl-phenosafranine (Amethyst violet). 
Creso-safranine. 

Naphtho-phenosafranine. 

Ethyl-dimethyl-etho-safranine (Fast neutral violet D). 


The following bodies also exert a strong desensitizing 
action: 


Toluylene red, 1: 1,000 solution; immersion for 4 minutes. 
Aurantia (ammonium salt), 1: 1,000 solution. 

Picric Acid, 1 per cent. solution. 

Indian Yellow, 2 per 1,000 solution. 

Crysoidine, 1: 2,000 solution. 

Diamidophenol, 1 per cent. solution. 

Apomorphine hydrochloride, 1 per 1,000 solution. 
Neutral potass chromate, 2 per cent. solution. 


Plates may also be desensitized with Potassium 
Iodide according to Freund’s method. This method is not 
very satisfactory. 


FILTER DYES 


Recently Hnatek has given a very complete collection 
of dyes and their applications for filter-making that cover 
the whole of the spectrum and are applicable to all classes 
of photographic work where contrast or compensating 
filters and safe lights are necessary: 


MATERIA PHOTOGRAPHICA 


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92 MATERIA PHOTOGRAPHICA 


The dyes were made up into stock solutions of the 
following strengths: 


0.4-100 Acid green. 


0.5-100 Brilliant orange, martius yellow, brilliant green, 
methyl green, methylene blue, toluidin blue, gentian 
violet. 


1-100 Fast red, D. Bordeaux, rose bengal, naphthol 
yellow, chinolin yellow, rapid filter yellow K, auramin, 
naphthol green, light green, alkali blue, patent blue, Hof- 
mann’s violet. 


2-100. New coccin, eosin, tartrazine. 


The second column gives the band of transmission of 
the filter, the fourth gives the number of cubic centi- 
meters that should be added to 7 cc. of 12 per cent. solu- 
tion of gelatin, and this is the quantity that should be 
coated on 100 square centimeters of glass. 


The fifth column gives the quantity of dry dye in 
grams per square meter, according to Huebl, which is 
called the density of the dye. 


The last column gives useful data as to the transmis- 
sion of the red end of the spectrum, which for visual work 
is negligible, but for photographic work must be taken 
into consideration, when panchromatic plates are used. 


Filters 9, 29 and 32 are rather dark, that is to say, 
they exert some absorption of the region that they gen- 
erally transmit; 10, 17, 28 and 31 are less dark, but still 
do not transmit to the full the wave lengths given. 


It is obvious that by combination of two or more 
filters almost monochromatic filters can be obtained, but 
in all cases the resultant filters are very dark. 


The signs (a) and (b) mean that the dyed gelatine 
must be coated on two separate glasses and that they can- 
not be mixed. 


MATERIA PHOTOGRAPHICA 93 


For the preparation of orthochromatic filters similar 
to the K series, Filter Yellow K is the dye used. A filter 
about equivalent to K2 can be prepared as follows: 


MOPITEIMOPSGIULION Asc lees un eee ele es 6% 
LORE? NPE can «gn rr 1 to 200 sol. 


(Rapid Filter Yellow) 


For Orthochromatic Emulsions: 


selatnersoiition «...0s.0 6.5. e5 eco s 120 cc. 
RE MER ONITIOU S252 c Sina win tees cae ss oes 66° cc: 
et eM ce. 5s She vGeieidiw owes x 6. Gc: 


Use 7 cc. of dyed gelatine to 1 sq. decimeter plate sur- 
face and use two of the coated glasses cemented together, 
or use 14 cc. dyed gelatine to 1 sq. decimeter and cement 
to a plain glass. 


Lighter or darker filters may of course be obtained by 
decreasing or increasing the amount of dye. Filter Yellow 
K aes be replaced by the English dye (Ilford Ltd.) Filter 
Yellow A. 


FILTERS FOR THREE COLOR WORK. 


Stock Solutions: 


Blue— 

OL! AE 4 grams 

SO Aes er aU Cr: 

PT Atia LCehico ACI ...2 0.60. hres 5 or 6 drops 
Green— 

UPS IS ee Og ce | 1 gram 

ee OO WW ya is ce 81s eos ein 1 gram 
Lo NST Se er 100 ce, 
Red— 

mecaeiiter Red To... i. scenes 5 grams 

ails cr ne a 8% a8 oes we Z00R ec: 
Dyed Gelatine— 

PROMS ONITIO Rie sons «ek Sine nie os en os 20. cc, 

Geélatine ‘Solution 6%...........«. 100 cc. 


7 ccs, to 100 sq. cm. 
Cement two of each filter together. 


94 MATERIA PHOTOGRAPHICA 


DARK ROOM FILTERS—BASED ON 16 C. P. LAMP 


For use with Developing Papers: 


Transmits 515 to 800 
TLartrazine:..20). 2. .veo0 eo eee 0.8 grams 
Gelatine ‘Sol'6%73 720. eee 60.0 cc. 


_ Coated on a glass 8 x 10. Bind two together with 
onion skin paper between. 


For Bromide Papers and Lantern Plates: 


Transmits 575 to 800 


Glass No. 1— 
Gelatine Sol?.6%.. 283.4. ee 60.0 cc. 
‘Tartrazine #48 ss oer ee eee 0.8 grams 
Glass No. 2— 
Gelatine Sol. (6% <... : os. oi. ccn eee 60.0 cc. 
Rose’ Bengal... cg. 2553 eee eee 0.3 grams 


Bind 1 and 2 with tissue—8 x 10 glass. 


Rapid Ordinary Plate 


Transmits 620 to 800 
Glass No. 1—8 x 10 


Gelatine Sol. 6%... . 2502 ec. 60.0 cc. 

Tartrazine 6.5.9 3k 4 eee 0.8 grams 
Glass No. 2— 

Gelatine’ Sol. 6%... cs sas se ae 60.0 cc. 

Xylene Rede G2. <a 0.8 grams 


Bind with tissue. To darken soak the tissue in Methyl 
Violet solution; use double quantity. Trans. 650 to ese 
Suitable for ortho emulsions. 


The equivalents in other dyes of 0.8 grams of tartrazine: 


Brilliant- Yellow (3... eg ee 0.4 grams 
Naphthol “Yellow 3. 2.4.32) 0.8 grams 
Auramine’ Yellow. ...... 4... sen le eee 1.6 grams 


Instead of Xylene Red 0.8, may use 0.6 grams Rose 
Bengal. 


MATERIA PHOTOGRAPHICA 95 


Green for Panchromatic Plates © 


SS ee en 1 gram 
Pepore ne 12 1000 soli... coe... ee 4 ce. 
MOPERINT MEM A SOL Sass sce tice aman ws’ 90 cc. 


Use 7 cc. to 100 sq. cm. of glass. Bind two together 
with tissue 


DYES FOR TINTING MOTION PICTURE FILM, 
LANTERN SLIDES AND TRANSPARENCIES 


A number of dyes are supplied especially for tinting 
or staining. ‘Those most frequently used for motion pic- 
ture positives being Cine Red, Cine Scarlet, Cine Orange, 
Cine Yellow, Cine Green and Cine Blue. 


The following dyes made by the National Aniline 
Chemical Company are also used for tinting films: Saf- 
ranine 6B, Methylene Blue SP, Methyl Violet 2B Conc. 
Pdr., Chrysoidine Y Extra, Safranine A, Victoria Green 
WB Pdr., Auramine O, Fuchsine NB Pdr. Almost any 
tint can be obtained by the proper combination of two 
or more of these dyes. : 


96 MATERIA PHOTOGRAPHICA 


CONVERSION TABLES 
With Weights and Measures 


Milliieter soc: 3a ee ee eee 0.04 inch 
Centiméter. on a ee ee ee 0.39 inch 
Inch. fo ee i eee 254 2 °cnr 

Poot ss. 2 ees eee ee 0.3048 meter 
Vard'. poise ee ete oe ee 0.9144 meter 
Miles. Cite 6S se eee 1.6093 kilometer 
Meter clk iege ie Smee econ eee ee 39.34  inehes 
Meter yao 2 ee ees Deer rr, 3.2808 feet 
Meterisc eae. Soe eee 1.0936 yards 
Kilometetic3% gon kuec oe eee ee 0.6214 mile 
sdiuare neh she. ce ee ee 6.45 sq. cm. 
Square Foot os acces ae we ee 0.0929 sq. meter 
Square vy ards so eae ee eee 0.836 sq. meter 
Qunee Avoirdupois..5 o.... ee ee 28.35 grams 
Ounce Troy and Apothecaries........ 31.103 grams 
PoundcAvoirdupois......e.es eee 453.59 grams 
PoundLroy..s 220 cone oh Soe 373.2 grams 
(GAIT eee es Ss ae ee 15.432 grains 
Kilogram. fon8. do% Sao ee ee 2.205 lbs. Avoir. 
Kilogram... eee eee 2.679 lbs. Troy 
Ounce: (uid) 5225.2 ee ee eee 29.574 cc. 
Quarts iia k sae ee ee 0.9464 liter 
Gallon :U, Sis wives 3.7854 liters 
Liter. oo ee ee eee 1.0567 quart 
Lifer 25 es sci roe ee 0.2642 gallon 
Cubic Inch. 24 64 en ee eee 16.387 cc. 

Cubic Foot... 2: 2e. 2 eee 28.3 liters 
Ounce -Avoirdtipois..2<) a, 2 eee 437.5 grains 
Ounce Troy and Apothecaries........ 480.0 grains 
Gallon (Us 8.743 See eee 231.0 cu. inches 
GallontU?-S.- Water. 4, eee 8.337 Ibs. 
Cubic: Poot. co .ncese se ee eee 7.48 gallons 
Cubic: Foot Water... 4... 4.5 et eee 62.426 lbs. 


CONVERSION RULES 

Grams per liter into grains per ounce: 

Multiply the grams by 0.44. 
Ces. per liter into minims per ounce: 

Divide the ccs. by 2 (more exactly, multiply by 0.48). 
Grains per ounce into grams per liter: . 

Multiply the grains by 2.3. Thus 50 grs. per oz. = 115 

gms. per liter. 


Minims per ounce into ccs. per liter: 
Multiply the minims by 2. 


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“Made Better in America” 


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T has long been customary for the 
agents of certain foreign chemical 
houses to belittle the rapid growth 
and development of the American 
Chemical Industry. Some of their 
geers may have been justified years 
ago, when the industry was still in 
its swaddling clothes. 


To-day, however, particularly in 
the field of photographic chemicals, 
American manufacturers refuse to 
admit foreign superrority in either 
price or quality. 

Send for generous FREE 


samples of our 


RHODOL and 
HYDROQUINONE 


and convince yourself. 


RHODIA CHEMICAL COMPANY 
89 Fulton Street - New. York, N. Y. 


ABE COHEN’s EXCHANGE, 113 PARK Row, New York 


Materia Photographica 


The Camera 


Select your camera or lens from our ample stocks 
of Kodaks, Graflex, Ansco, Ica and Goerz Cameras. 
The world’s best makes of lenses always in stock. 
Carl Zeiss, Goerz, Bausch & Lomb, Voigtlander, Dall- 


meyer and other makes; soft focus and portrait lenses. 


Exposure 


Complete line of Exposure Meters, Color Filters, 
Portrait Attachments, Diffusing Disks, Flash Guns 
and Flash Outfits. 


Developing, Printing and Enlarging 


Let us furnish all you require in roll film and plate 
tanks, Developing and Fixing Chemicals, Dark Room 
Lamps, Automatic Printers, Trays, Printing Frames, 
Photographic Papers, Enlarging Cameras, Condensing 
Lenses, Parallax Reflectors. 


Pictorial Photography 


We have everything for the Pictorial worker, in Brom- 
oil, Carbro, Kallitype and other processes, including 
all Enlarging Papers, bleachers, chemicals, transfer 
papers, bromoil brushes, inks, and other. accessories. 


Write and tell us your wants 


—— Ape CoHENS EXCHANGE | 


113 PARK Row, NEW YORK 


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_ furnish you anywhere, at any time, a soft, powerful light 


‘and on groups, banquets and interiors, the 


Victor Flash Powder 


“The Light That’s Always Available’’ 


A majority of your negatives are made indoors, and 
daylight seldom strongly or uniformly lights any interior, 
and never permits the instantaneous exposures necessary 
to prevent movement and secure desired animation of 
your subjects. 


You can, however, easily overcome this handicap by 
using Victor Flash Powder as your exposure-light. It will 


which you can regulate in volume and direction to exactly 
suit the character and requirements of your subjects. 


All your exposures with Victor Flash Powder are in- 
stantaneous, enabling you to unfailingly catch desired 
expressions and poses of even the most active subjects. 


The amount of illumination you secure is merely a 
matter of the quantity of Victor Powder you use. For 
portrait work, 3 to 10 grains is sufficient, 


amount required is surprisingly small. 
Secure a supply now, that you may con- 
stantly have it on hand to assist you. 


Is supplied in four grades to meet all 
requirements, viz.: Normal, Extra Fast, Soft } 
and Portrait. Normal is most satisfactory | 
for general use. 


We manufacture a complete line of Hand 
Flashlamps, Flash Bags and Studio Flash 
Cabinets, description of which will be gladly 
sent on request. 


JAMES H. SMITH @ SONS CO. 
3529 Cottage Grove Ave. CHICAGO, ILLINOIS 


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In no other photographic magazine 
can you find so much plain and 
practical information 


as in 


THE MAGAZINE LE LUXE FOR ALL PHOTOGRAPHERS 


HE pictorial reproductions in THE CAMERA are by 
the best workers in America and abroad. Every 
issue is a veritable work of art. 


If you want a print criticised or are puzzled about a 
working formula, just ask THE CAMERA—it is at your 
service. 


THE CAMERA is for sale by dealers at 20 cents per — 
copy or $2.00 per year by subscription. If your dealer 


cannot show you a sample copy, send five 2-cent stamps 
to the publisher for one. 


FRANK V. CHAMBERS 


Corner Seventh and Race Streets 


PHILADELPHIA 


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THERE’S A GRADE 
Beinee VERY PURPOSE 


O matter what the need, there’s a grade and surface 
of HALOID QUALITY PAPER with which to 
meet it. The most exacting studios, the busiest finishers 


and commercial photographers, all find in the HALOID 


line, solution to their paper problem. 


Briefly classified the HALOID grades are these: 


Haloid Portraya 


for portraits in warm black. 


Haloid Enlarging Portraya 

for prints by enlargement that es- 

cape the “‘enlarged”’ appearance. 
Haloid Outline Special 


Very thin tough stock. For fur- 

niture and other commercial 

prints. Will not crack when 
folded. A unique product. 


Haloid Parchment Antique 


A unigue portrait paper of 
‘*hand-made”’ appearance. 


Haloid Industro 


A remarkably effective paper 
for popular-priced portraits. 


Haloid Press Bromide 


A fast and very contrasty bro- 
mide paper. Single and Double 
Weight Glossy. 


Haloid Fine-Fabric Linen 
(buff or white) 


Fine-textured linen papers for 
de luxe portraits. 


Haloid Art-Proof 


P. O. P. papers of unequalled 
guality for proofing. 


Haloid Rito 


Non-abrasive papers of wide 

latitude for finishing and com- 

mercial work. Now made in 
four degrees of contrast. 


THE HALOID COMPANY, Rochester, N. Y. 


NEW YORK OFFICE: 225 Fifth Avenue 
CHICAGO OFFICE: 68 W. Washington Street 
BOSTON OFFICE: IOI Tremont Street, at Bromfield 


San Francisco Agent: 


A. H. MUHL, 143 Second Street 


Los Angeles Agent: 
A. H. MUHL, 643 S. Olive Street 


MERCK’S 
Photographic Developers 


FOR PROFESSIONAL AND 
AMATEUR PHOTOGRAPHERS 


Photol (Monomethyl-Paramido- Phenol Sulphate) 


Widely used in developing negatives, Velox and 
other developing-out papers. 


Hydroquinone 


Beautiful, light, needlelike crystals. Particularly use- 
ful in developing papers, and in motion picture work. 


Acid Pyrogallic 
Finest detail in lights and shades. Most perfect 


printing negatives. 


Price list on request 


MERCK & CO. 


St. Louis New York Montreal 
Works at Rahway, N. J. 


THERE IS A 


CRAMER PLATE 


FOR EVERY NEED 


25 BRANDS OF UNEQUALLED QUALITY 


Sao? 
CONY 9D 
Write for a copy of our “Manual.” | 


It briefly describes all 25 brands 


and is full of useful information. 


COA DSS 
GC aed 


G. CRAMER DRY PLATE COMPANY 


NEW YORK ST. LOUIS CHICAGO 


PHOS SEH SP SESH ESS SPIN SESS SOS! OPH EMO OLIN SLIH OLN SPIN OLLI SLOP SPSL OLS PLIN SLO SPONSE PS (SSO SSS SPONSES SSC SSS SESH See 116 


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The News of the 
Photographic World— 


may be brought to your desk 
every Wednesday of the year 
through the pages of the 


IBULLETIN ~ OF] 
IPHOTOGRAPHY| 


It keeps you enlightened on | 
every-day progress—tells you | 
what the rest of the world is 

doing in photography—and | 
gives you the news most es- 

sential, most interesting and | 
most vital to your business. 


PUBLISHED EXCLUSIVELY PORSTHE 
PROFESSIONAL PHOTOGERAR A. 


Subscription price, $2.00 per year, postpaid 


BULLETIN OF PHOTOGRAPHY 
FRANK V. CHAMBERS, PustisHER 


636 FRANKLIN SQUARE, PHILADELPHIA 


WOULD YOU LIKE A 3A 


Se PSC Sweieweteoe ete 6 4 CERIO 4 ORE 6 ENED | KRRIE 4 6 AER | | PR 1 RE | HOEY | m6 SH | HSS + GE | | AD + 1 Em | GE Den | SRD 1 + OY se 


W OLLENSAK LENSES 


JUST A FEW OF THE MANY POPULAR TYPES 


—for all-round studio use and Graflex 


as well as home portraiture, the Series II Velostigmat 4.5 is 
ideally suited. It capably handles bust and child portraits, 
full figures and groups, and is adaptable to commercial work, 
copying, enlarging, etc. 


—for delightful soft-focus effects 


nothing compares with the Verito Diffused Focus f4. This 
versatile objective gives as much or as little diffusion as 
may be desired by simply turning the diaphragm ring, 
Long focus rear element. 


—for portraiture and baby pictures 


the Vitax Portrait 3.8 stands supreme. Its improved 
Petzval formula helps to produce life-like portraits 
with beautiful modeling. Its extreme speed permits 
snap shots in the studio. 


—for commercial and view work 


we recommend the new Series Ia Velostigmat f6.3--f7.7. 
This is a wonderful triple-convertible anastigmat. Its 
long-focus single elements are also fully corrected and 
‘ aid in obtaining telephoto effects, better perspective 
and larger images. 


—for wide-angle photographs 


we offer the Series III Velostigmat. It has the unusual 
speed of f9.5 and an angle of 90 degrees. A truly valuable 
addition to any equipment. 


If you wish descriptive catalog of the complete Wollensak 
line of lenses and shutters, write to the 


WOLLENSAK OPTICAL COMPANY ~- Rochester, New York 


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IWENTIETH CENTURY PHOTOGRAPHY 


THE WILLSON WAY 


Willson 
Apparatus 
Solves 

The 

Profit 
Problem 


WILLSON MAGAZINE CAMERA 

Capacity, 1,100 exposures at one loading 

GROUP PICTURES FROM ORIGINAL NEGATIVES 
LARGE PICTURES FROM SMALL NEGATIVES 


IDENTIFICATION 


Write 


for 
Catalog 


_WILLSON AUTOMATIC PRINTER 


| VICAM PHOTO APPLIANCE CORPORATION 


1224 BELMONT AVENUE, PHILADELPHIA, PA. 


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